is equal to:
A. 3
B. 4
C. 5
D.
A ribbon of lengthm is cut into small pieces each of lengthm. Number of pieces will be:
A. 5
B. 6
C. 7
D. 8
Length of ribbon= m
Length of each piece= m
Number of piece
7 pieces
The ascending arrangement of is:
A.
B.
C.
D.
First we need to find the L.C.M of denominator
L.C.M.= 21
We have to make the denominator equal to the L.C.M for all the fractions by multiplying same number in numerator and denominator.
Ascending arrangement:
Reciprocal of the fractionis:
A. 2
B. 3
C.
D.
The reciprocal is obtained by interchanging the number at numerator and denominator position.
Reciprocal is
The product ofand 4 is:
A.
B.
C.
D.
× 4
The product of 3 andis:
A.
B.
C.
D.
3 × 4
Pictorial representation of is:
A.
B.
C.
D.
means 3 pictures in which two-third of each picture is selected
We find only option B has such pictorial representation
equal to:
A.
B.
C.
D.
The product of 0.03 × 0.9 is:
A. 2.7
B. 0.27
C. 0.027
D. 0.0027
3×9=27
Since the decimal point has shifted two places left of 3 and one place left of 9 so we have to move three places towards left in case of 27
0.027
is equal to:
A.
B.
C.
D.
÷6
is equal to
A.
B.
C.
D.
Which of the following representsof
A.
B.
C.
D.
The word ‘of’ means multiplication between the two fractions
ofis equal to
A.
B.
C.
D.
One packet of biscuits requirescups of flour andcups of sugar. Estimated total quantity of both ingredients used in 10 such packets of biscuits will be
A. less than 30 cups
B. between 30 cups and 40 cups
C. between 40 cups and 50 cups
D. above 50 cups
Flour Required = cups
Sugar required = cups
Total quantity of ingredient for one packet
⇒ Total quantity of ingredient for one packet cups
⇒ Total quantity of ingredient for 10 packet cups
It requires 40 to 50 cups of ingredients
The product of 7 andis
A.
B.
C.
D.
7 × 6
On dividing 7 bythe result is
A.
B.
C.
D.
7÷
is equal to
A.
B.
C.
D.
÷ 5
of 5 kg apples were used on Monday. The next dayof what was left was used. Weight (in kg) of apples left now is
A.
B.
C.
D.
Amount of apple used on Monday= of 5
Remaining apple =(5-4)= 1 kg
Amount of apple used the next day = of 1
Weight of apples left now
The picture
Interprets
A.
B.
C.
D.
Shaded region of each picture on the left side
Total no. of pictures on the left = 3
Total value
Fill in the blanks to make the statements true.
Rani ate part of a cake while her brother Ravi ateof the remaining. Part of the cake left is __________
The amount of cake at the beginning =1
Part of cake Rani ate
Part of the cake left after Rani ate
Part of the remaining cake Ravi ate
Part of the cake left after both ate
Fill in the blanks to make the statements true.
The reciprocal of is ___________
The reciprocal is obtained by interchanging the number at numerator and denominator position.
Reciprocal is
Fill in the blanks to make the statements true.
of 27 is ___________
of 27
⇒ 2×9=18
18
Fill in the blanks to make the statements true.
of 45 is ______
of 45
⇒ 4×9=36
36
Fill in the blanks to make the statements true.
4 × 6is equal to _______
4 × 6
Fill in the blanks to make the statements true.
ofis _______
Fill in the blanks to make the statements true.
ofis ______
Fill in the blanks to make the statements true.
The lowest form of the productis________
Fill in the blanks to make the statements true.
÷ 4 is equal to _______
Fill in the blanks to make the statements true.
of 25 is ________
of 25
⇒ 2×5=10
Fill in the blanks to make the statements true.
Multiplication (×)
Division of two fractions is same as multiplying the first fraction with the reciprocal of second fraction.
Fill in the blanks to make the statements true.
3.2 × 10 = _______
32
We have to shift the decimal place to the right by one place since 10 has only one zero
Fill in the blanks to make the statements true.
25.4 × 1000 = _______
25400
We have to shift the decimal place to the right by three places since 1000 has only three zeroes
Fill in the blanks to make the statements true.
93.5 × 100 = _______
9350
We have to shift the decimal place to the right by two places since 100 has only two zeroes
Fill in the blanks to make the statements true.
4.7 ÷ 10 = ______
0.47
We have to shift the decimal place to the left by one place since 10 has only one zero
Fill in the blanks to make the statements true.
4.7 ÷ 100 = _____
0.047
We have to shift the decimal place to the left by two places since 100 has only two zeroes
Fill in the blanks to make the statements true.
4.7 ÷ 1000 = ______
0.0047
We have to shift the decimal place to the left by three places since 1000 has only three zeroes
Fill in the blanks to make the statements true.
The product of two proper fractions is _______ than each of the fractions that are multiplied.
less
The value of a proper fraction is always less than 1. So when they are multiplied the value is less than each of the two fractions.
Fill in the blanks to make the statements true.
While dividing a fraction by another fraction, we _________ the first fraction by the _______ of the other fraction.
Multiply, Reciprocal
Division of two fractions is same as multiplying the first fraction with the reciprocal of second fraction.
Fill in the blanks to make the statements true.
8.4 ÷ ______ = 2.1
4
The divisor can be found by dividing the dividend by quotient
Fill in the blanks to make the statements true.
52.7 ÷ _______ = 0.527
100
The Decimal has shifted two place towards left. So the number is divided by 100.
Fill in the blanks to make the statements true.
0.5 _____ 0.7 = 0.35
0.5× 0.7=0.35
× (Multiplication)
Fill in the blanks to make the statements true.
2 ____
÷(Division)
Fill in the blanks to make the statements true.
2.001 ÷ 0.003 = __________
667
State whether the statement is True or False.
The reciprocal of a proper fraction is a proper fraction.
It is a false statement
The value of a reciprocal of a proper fraction is always greater than 1 and hence it is an improper fraction.
State whether the statement is True or False.
The reciprocal of an improper fraction is an improper fraction.
It is a false statement
The value of a reciprocal of an improper fraction is always less than 1 and hence it is a proper fraction.
State whether the statement is True or False.
Product of two fractions =
It is a true statement
Product of more than one fraction is found my multiplying all the numerator and all the denominators.
State whether the statement is True or False.
The product of two improper fractions is less than both the fractions.
It is a false statement
The value of an improper fraction is always greater than 1 and hence its product with another improper fraction is always greater than the two fractions.
State whether the statement is True or False.
A reciprocal of a fraction is obtained by inverting it upside down.
It is a true statement
The reciprocal is obtained by interchanging the number at numerator and denominator position.
State whether the statement is True or False.
To multiply a decimal number by 1000, we move the decimal point in the number to the right by three places.
It is a true statement
Since multiplication by 1000 is similar to multiplying by 10 three times, so we have to move the decimal place towards right by three places.
State whether the statement is True or False.
To divide a decimal number by 100, we move the decimal point in the number to the left by two places.
To divide a decimal number by 10, 100 or 1000, we shift the decimal point in the number to the left by as many places as there are zeroes over 1, to get the quotient.
∴ This statement is True.
State whether the statement is True or False.
1 is the only number which is its own reciprocal.
Since 1 can be written as , and we know that reciprocal of a fraction is obtained by interchanging the numerator and denominator of fraction, therefore reciprocal of is 1 only.
∴ This statement is True.
State whether the statement is True or False.
of 8 is same as÷ 8.
As we know that, ‘of’ operator in fraction is used for its multiplication,
When dividing a whole number by a fraction, we multiply the whole number by the reciprocal of that fraction.
∴ This statement is false.
State whether the statement is True or False.
The reciprocal ofis
As we know that reciprocal of a fraction is obtained by interchanging the numerator and denominator of fraction.
∴ this statement is False.
If 5 is added to both the numerator and the denominator of the fractionwill the value of the fraction be changed? If so, will the value increase or decrease?
If 5 is added to both the numerator and the denominator of the fraction , the value would become and as .
∴ The value of fraction changes and it gets increased.
What happens to the value of a fraction if the denominator of the fraction is decreased while numerator is kept unchanged?
Let the original fraction be .
Now, if denominator is decreased (say by 1) while numerator is kept same, the fraction becomes .
As the value of fraction is inversely proportional to the value of denominator, therefore, by decreasing denominator the value of fraction increases.
Which letter comesof the way among A and J?
Since the number of letters from A to J are 10, therefore,
⇒ 4th letter from A comes 2/5 of way, which is letter D.
∴ Letter D is the required answer.
Ifof a number is 10, then what is 1.75 times of that number?
Let the number be A.
It is given that,
Also, 1.75 of A = 1.75 × 15 = 26.25
∴ Required answer is 26.25
In a class of 40 students,of the total number of students like to eat rice only,of the total number of students like to eat chapatti only and the remaining students like to eat both. What fraction of the total number of students like to eat both?
Total number of students in class = 40
Let the number of students that like to eat rice only be x.
Let the number of students that like to eat chapatti only be y.
Students that like both rice and chapatti are = 40 – x – y
⇒ 40 – 8 – 16
⇒ 40 – 24
⇒ 16
∴ 16 students like both rice and chapatti.
Renu completedpart of her home - work in 2 hours. How much part of her home -work had she completed inhours?
Part of homework completed in 2 hours =
Part of homework completed in 1 hour would be =
As we know , therefore,
Part of homework completed in hours would be =
∴ Renu must have completed 1/3 of her homework in hours.
Reemu readth pages of a book. If she reads further 40 pages, she would have readth pages of the book. How many pages are left to be read?
Let the total number of pages in the book be x.
Pages read by Reemu =
If she reads further 40 pages, she would have readth pages of the book,
On cross-multiplying, we get,
⇒ 5x = 400
⇒ x = 80
∴ Pages read by Reema = Total pages – Pages read
⇒ Required answer =
∴ 24 pages are left to be read.
Write the number in the box such that
Let the number in box be A.
We know, When dividing one fraction by another fraction, we multiply the first fraction by the reciprocal of the other.
Will the quotientbe a fraction greater than 1.5 or less than 1.5? Explain.
Let the quotient be A.
We know, when dividing one fraction by another fraction, we multiply the first fraction by the reciprocal of the other.
Since,, therefore the quotient of given fraction is greater than 1.5
Describe two methods to compareand 0.82. Which do you think is easier and why?
Method 1:
Convert the into a decimal value, which comes out to be 0.76.
This means is smaller than 0.82
Method 2: Convert 0.82 to a fraction form =
Making denominator of both fractions to its LCM,
LCM of 50 and 17 = 850
Also,
So, , therefore,
13/17 is smaller than 0.82
Health: The directions for a pain reliever recommend that an adult of 60 kg and over take 4 tablets every 4 hours as needed, and an adult who weighs between 40 and 50 kg take onlytablets every4 hours as needed. Each tablet weighsgram.
a) If a 72 kg adult takes 4 tablets, how many grams of pain relievers he or she receiving?
b) How many grams of pain reliever is the recommended dose for an adult weighing 46 kg?
(a)
∴ A 72kg of adult takes 0.64gm of pain relievers.
(b) An adult of 42 kg of weight should take tablets.
As the weight of each tablet = 4/25 grams
⇒ Weight of tablets =
∴ 0.20 grams of pain reliever is the recommended dose for an adult weighing 46 kg.
Animals: The label on a bottle of pet vitamins lists dosage guidelines. What dosage would you give to each of these animals?
a) A 18 kg adult dog
b) A 6kg cat
c) A 18 kg pregnant dog
a) As the dosage listed for adult dog is 1/2 tsp per 9 kg dog weight.
⇒ Dosage needed for 18 kg adult dog will be =
An 18 kg adult dog will have 1 tsp of dosage.
b) As the dosage listed for cat is 1/4 tsp per 1 kg dog weight.
⇒ Dosage needed for 6 kg cat will be = 1/4 × 6
An 18 kg adult dog will have 1.5 tsp of dosage.
c) As the dosage listed for pregnant dog is 1/2 tsp per 4.5 kg dog weight.
⇒ Dosage needed for 18 kg adult dog will be =
An 18 kg adult dog will have 2 tsp of dosage.
How manykg boxes of chocolates can be made withkg chocolates?
Weight of each box = kg
Total weight of chocolates = kg
Number of boxes of chocolates that can be made
As we know, when dividing one fraction by another fraction, we multiply the first fraction by the reciprocal of the other.
⇒ 3 × 8 = 24 boxes
∴ 24 chocolate boxes can be made.
Anvi is making bookmarker like the one shown in Fig. 2.6. How many bookmarker can she make from a 15 m long ribbon?
Length of each bookmarker
Total length of ribbon = 15m
Number of bookmarker
As we know, when dividing one fraction by another fraction, we multiply the first fraction by the reciprocal of the other.
∴ Anvi can make 142 complete bookmarkers.
A rule for finding the approximate length of diagonal of a square is to multiply the length of a side of the square by 1.414. Find the length of the diagonal when :
a) The length of a side of the square is 8.3 cm.
b) The length of a side of the square is exactly 7.875 cm.
a) Length of side of square = 8.3 cm
Length of diagonal = Length of square × 1.414
⇒ Length of side = 8.3 × 1.414 = 11.74 cm
b) Length of side of square = 7.875 cm
Length of diagonal = Length of square × 1.414
⇒ Length of side = 7.875 × 1.414 = 11.14 cm
The largest square that can be drawn in a circle has a side whose length is 0.707 times the diameter of the circle. By this rule, find the length of the side of such a square when the diameter of the circle is:
a) 14.35 cm
b) 8.63 cm
a) Diameter of the circle = 14.35cm
Length of side of square = 0.707 × 14.35 = 10.14 cm
b) Diameter of the circle = 8.63cm
Length of side of square = 0.707 × 8.63 = 6.101 cm
To find the distance around a circular disc, multiply the diameter of the disc by 3.14. What is the distance around the disc when :
a) the diameter is 18.7 cm?
b) the radius is 6.45 cm?
a) The diameter of the disc = 18.7 cm
Distance around the disc = 18.7 × 3.14 = 58.72 cm
b) The diameter of the disc = 6.45 cm
Distance around the disc = 6.45 × 3.14 = 20.25 cm
What is the cost of 27.5 m of cloth at 53.50 per metre?
Rate of cloth = Rs. 53.50 per m
Cost of 27.5 m cloth = Rate × 27.5
⇒ 53.50 × 27.5 = 1471.25
∴ Required cost of cloth is Rs. 1471.25
In a hurdle race, Nidhi is over hurdle B andof the way through the race, as shown in Fig. 2.7.
Then, answer the following:
a) Where will Nidhi be, when she isof the way through the race?
b) Where will Nidhi be when she isof the way through the race?
c) Give two fractions to tell what part of the race Nidhi has finished when she is over hurdle C.
Since when Nidhi has completed 2/6 of the race, She is at hurdle B, this means the hurdles are placed equidistant from each other and as there are six hurdles, the race is divided into six parts.
a) So, when she is of the way through the race, she will be at hurdle D.
b) When she is of the way through the race, she will be at hurdle E.
c) When Nidhi is over hurdle C, then she would have completed of the way.
Or, as she is half way through the race, she would have completed 1/2 of the race.
∴ Two fractions to tell what part of the race Nidhi has finished when she is over hurdle C will be and .
Diameter of Earth is 12756000m. In 1996, a new planet was discovered whose diameter isof the diameter of Earth. Find the diameter of this planet in km.
As 1000m = 1km,
Diameter of earth, D = 12756000m = 12756km
Diameter of planet = d
⇒ 0.058 × 12756 km
⇒ 739.848 km
∴ Diameter of this planet is 739.848 km
What is the product ofand its reciprocal?
As we know that reciprocal of a fraction is obtained by interchanging the numerator and denominator of fraction.
Product of given number and its reciprocal,
∴ Product of a number and its reciprocal is always equal to 1.
Simplify:
Converting the mixed fractions to simple fractions.
Solving the numerator,
Now, Solving Denominator, we get,
Putting the numerator and denominator in the fraction, we get,
As we know, when dividing one fraction by another fraction, we multiply the first fraction by the reciprocal of the other.
Simplify:
On solving Numerator of given fraction, we get,
On solving the denominator, we get,
Putting the value of numerator and denominator in given fraction, we get,
As we know, when dividing one fraction by another fraction, we multiply the first fraction by the reciprocal of the other.
Divideby
On simplifying the brackets, we get,
So, the question reduces to
As we know, when dividing one fraction by another fraction, we multiply the first fraction by the reciprocal of the other.
of a number equalsWhat is the number?
Let the number be x.
Solving the equals part first, we get,
As we know, when dividing one fraction by another fraction, we multiply the first fraction by the reciprocal of the other.
Now, according to question, it is given that,
⇒ x = 8 × 8 = 64
∴ the number is 64.
Heena’s father paid an electric bill of 385.70 out of a 500 rupee note. How much change should he have received?
Total money given by Heena’s dad = Rs. 500
Amount of electricity bill = Rs 385.70
Money returned to her father = 114.30
Change he received should be 30 paise.
The normal body temperature is 98.6°F. When Savitri was ill her temperature rose to 103.1°F. How many degrees above normal was that?
Normal body temperature = 98.6° F
Savitri temperature = 103.1° F
Temperature above normal =
∴ Rise in temperature was 4.5° F
Meteorology: One measure of average global temperature shows how each year varies from a base measure. The table shows results for several years.
See the table and answer the following:
a) Order the five years from coldest to warmest.
b) In 1946, the average temperature varied by –0.030C from the base measure. Between which two years should 1946 fall when the years are ordered from coldest to warmest?
a) In year 1978, the temperature was,
Multiplying both numerator and denominator by, we get
As we know that, to divide a decimal number by 10, 100 or 1000, we shift the decimal point in the number to the left by as many places as there are zeroes over 1, to get the quotient.
So, the temperature in year 1978 was 0.02° C.
Order of five years from coldest to warmest is:
1964 < 1965 < 1978 < 1958 < 2002
b) Since the temperature in 1946 was -0.03° C
Therefore, it lies between the year 1965 and 1978
-0.10 < -0.03 < 0.02
In her science class, Jyoti learned that the atomic weight of Helium is 4.0030; of Hydrogen is 1.0080; and of Oxygen is 16.0000. Find the difference between the atomic weights of:
a) Oxygen and Hydrogen
b) Oxygen and Helium
c) Helium and Hydrogen
Atomic Weight of Helium, He = 4.0030
Atomic Weight of Hydrogen, H = 1.0080
Atomic Weight of Oxygen, O = 16.0000
a) Difference between Oxygen and Hydrogen = O – H
⇒ Difference between Oxygen and Hydrogen is 14.9920
b) Difference between Oxygen and Helium = O – He
⇒ Difference between Oxygen and Helium is 11.9970
c) Difference between Helium and Hydrogen = He – H
⇒ Difference between Helium and Hydrogen is 2.9950
Measurement made in science lab must be as accurate as possible. Ravi measured the length of an iron rod and said it was 19.34 cm long; Kamal said 19.25 cm; and Tabish said 19.27 cm. The correct length was 19.33 cm. How much of error was made by each of the boys?
Correct length of rod, C = 19.33 cm
Length reported by Ravi, R = 19.34 cm
Length reported by Kamal, K = 19.25 cm
Length reported by Tabish, T = 19.27 cm
Error made by Ravi = R – C
Error made by Kamal = K – C
Error made by Tabish = T – C
∴ Error made by Ravi, Kamal and Tabish is 0.01cm, -0.08cm and -0.06 cm respectively.
When 0.02964 is divided by 0.004, what will be the quotient?
We can re-write the given decimals into fractions as:
Also, when they are divided,
As we know, when dividing one fraction by another fraction, we multiply the first fraction by the reciprocal of the other.
∴ the quotient will be 74.135
What number divided by 520 gives the same quotient as 85 divided by 0.625?
Let the number be x, so according to the question,
⇒ x = 520 × 136
⇒ x = 70720
∴ the number is 70720
A floor is 4.5 m long and 3.6 m wide. A 6 cm square tile costs 23.25. What will be the cost to cover the floor with these tiles?
Area of the entire floor, AF = 4.5 × 3.6 sq.m
Area of square tile, AT = 6 × 6 = 36 sq.cm
Number of tiles needed = AF / AT
Rate of tile = Rs 23.25
Total cost = Rate × tiles needed
Total cost of flooring is Rs 10462.5
Sunita and Rehana want to make dresses for their dolls. Sunita hasm of cloth, and she gaveof it to Rehana. How much did Rehana have?
Cloth Sunita has
She gave 1/3 of that to Rehana,
∴ Rehana have m of cloth.
A flower garden is 22.50 m long. Sheela wants to make a border along one side using bricks that are 0.25 m long. How many bricks will be needed?
Length of flower garden, L = 22.50 m
Length of brick, b = 0.25 m
As we know, when dividing one fraction by another fraction, we multiply the first fraction by the reciprocal of the other.
∴ 90 bricks are needed to make the border.
How much cloth will be used in making 6 shirts, if each requiredm of cloth, allowingm for waste in cutting and finishing in each shirt?
Cloth required for making one shirt = R metre
Cloth needed for 6 shirts = (R × 6) metres
∴ 14.25 m of cloth is required for making 6 shirts.
A picture hall has seats for 820 persons. At a recent film show, one usher guessed it was full, another that it was full. The ticket office reported 648 sales. Which usher (first or second) made the better guess?
Given:
Seats in picture hall = 820
Persons reported in hall = 648
Guess made by 1st user = full
Guess made by 2nd user = full
Formula Used\Theory:
Less the difference between guessed value and real value
More it will be a better guess.
⇒ The guess made by 1st user:-
full = × 820
= 3 × 205
= 615
Difference in reality and guessed = 648 – 615
= 33
⇒ The guess made by 2nd user:-
full = × 820
= 2 × 273.33
= 546.66
Difference in reality and guessed = 648 – 546.66
= 101.33
∴ The difference of guessed from reality is lower in 1st user
Conclusion:1st user made a better guessed
For the celebrating children’s students of Class VII bought sweets for ₹ 740.25 and cold drink for ₹ 70. If 35 students contributed equally what amount was contributed by each student?
Given:
Number of students in class = 35.
Price of sweets = Rs.740.25
Price of cold drink = Rs.70
Formula Used\Theory:
Dividing total amount by number of students gives
Contribution of each student
⇒ Total amount = Amount of cold drink + Amount of sweets
Total amount = Rs.740.25 + Rs.70
= Rs.810.25
⇒ Amount paid by 35 students = Rs.810.25
Amount paid by 1 student =
= Rs.23.15
Conclusion: Each student contributes Rs.23.15
The time taken by Rohan in five different races to run a distance of 500 m was 3.20 minutes, 3.37 minutes, 3.29 minutes, 3.17 minutes and 3.32 minutes. Find the average time taken by him in the races.
Given:
The time taken in 5 races are:
3.20 minutes, 3.37 minutes, 3.29 minutes, 3.17 minutes
3.32 minutes
Formula Used\Theory:
Average =
Number of timings of races = 5
Sum of timings of races =
(3.20 + 3.37 + 3.29 + 3.17 + 3.32) minutes
= 16.35
Average =
Average =
Average = 3.27minutes
Conclusion: Average time taken by Rohan is 3.27 minutes
A public sewer line is being installed along m of road. The supervisor says that the labourers will be able to complete 7.5 m in one day. How long will the project take to complete?
Given:
Length of road = m
Length of work labourer does in 1 day = 7.5m
Formula Used\Theory:
Dividing total length by length of work done in 1 day gives
Number of days to complete the work
7.5m Length of work done in⇒ 1 day
1m Length of work done in⇒ day
m Length of work done in⇒ × day
= ×
= ×
=
10.7days
Conclusion:10.7days are required to complete the work
The weight of an object on moon is its weight on Earth. If an object weighs kg on Earth, how much would it weigh on the moon?
Given:
The weight of an object on moon is its weight on Earth.
Weight of object is kg on Earth
Formula Used\Theory:
Multiplying the ratio of both with value of one object gives
Value of 2nd object
If the weight of an object on moon is its weight on Earth.
And weight of object is kg on Earth
Weight of object on earth = kg
= kg
∴ Weight on moon = kg
= kg
= 0.933kg
Conclusion: Weight of object on moon is 0.933kg
In a survey, 200 students were asked what influenced them most to buy their latest CD. The results are shown in the circle graph.
(a) How many students said radio influenced them most?
(b) How many more students were influenced by radio than by a music video channel?
(c) How many said a friend or relative influenced them or they heard the CD in a shop?
Given:
Number of students = 200
Formula Used\Theory:
Multiplying of ratio of each part and total value gives out
Value of each part
(a) The number of students influenced by radio is =
Ratio × total number of students
= × 200
= 9 × 10
= 90students
(b) Number of students influence more by radio than music video channel
= difference of ratio × number of students
= () × 200
= () × 200
=
= 37 × 2
= 74 students
(c) Number of students influence by friends and relatives
= Ratio × total number of students
= × 200
= 3 × 10
= 30
Number of students heard CD in a shop = Ratio × total number of students
= × 200
= 20 students
In the morning, a milkman filled L of milk in his can. He sold to Renu, Kamla and Renuka L each; to Shadma he sold L; and to Jassi he gave L. How much milk is left in the can?
Given:
Total milk milkman had in his can = L
Milk given to Renu, Kamla and Renuka is L each
Milk given to Shadma L
Milk given to Jassi L
Formula Used\Theory:
Difference of sold item from total gives
Value of remaining part
Renu, Kamla and Renuka is L each
Shadma L
Jassi L = L
Sum of milk sold is
L + L + L + L + L
[]L
L
L
= L
Milk left in his can = total milk – sold milk
= []L
= []L
= []L
=
=
= L milk
Conclusion: L of milk left in his can.
Anuradha can do a piece of work in 6 hours. What part of the work can she do in 1 hour, in 5 hours, in 6 hours?
Given:
Anuradha can do a piece of work in 6 hours
Formula Used\Theory:
Division of specific time with total time gives
The amount of work done in that time interval
Let X be a piece of work
If the work X is done in 6 hours
⇒ Then work done in 1 hour is
∴ Part of work X is done in 1 hours
If work done in 1 hour is
⇒ Then work done in 5 hours is
∴ Part of work X is done 5 hours
If work done in 1 hour is
⇒ Then work done in 6 hours is
∴ Whole Part of work X will be done 6 hours
What portion of a ‘saree’ can Rehana paint in 1 hour if it requires 5 hours to paint the whole saree? In hours? In hours?
Given:
Rehana requires 5 hours to paint the whole saree
Formula Used\Theory:
Division of specific time with total time gives
The amount of work done in that time interval
Let X be work of painting a saree
If the work X is done in 5 hours
⇒ Then work done in 1 hour is
∴ Part of work X is done in 1 hours
→ Hours = Hours = Hours
If work done in 1 hour is
⇒ Then work done in hours is
=
∴ Part of work X is done hours
→Hours = Hours = Hours
If work done in 1 hour is
⇒ Then work done in hours is
=
∴ Part of work X will be done hours
Rama has kg of cotton wool for making pillows. If one pillow takes kg, how many pillows can she make?
Given:
Rama has kg of cotton wool
Cotton wool taken by 1 pillow is kg
Formula Used\Theory:
Dividing total weight by weight of 1 item gives
Number of items
Cotton wool Rama had kg
= kg = kg
Cotton wool taken by 1 pillow is kg
= kg = kg
∴ Number of pillows = = = 5
Conclusion: 5 pillows can be constructed
It takes m of cloth to make a shirt. How many shirts can Radhika make from a piece of cloth m long?
Given:
Radhika has m cloth
Cloth require to make skirt is m
Formula Used\Theory:
Dividing total length by length of 1 skirt gives
Number of skirt
Length of cloth Radhika had kg
= kg = kg
Length of cloth require to make skirt is kg
= kg = kg
∴ Number of skirts = = = 4
Conclusion: 4 skirts can be constructed
Ravi can walk km in one hour. How long will it take him to walk to his office which is 10 km from his home?
Given:
Ravi can walk km in one hour
Distance to walk to his office from home is 10km
Formula Used\Theory:
Speed =
Time =
Speed = km in one hour
= = km in one hour
Distance = 10km
∴ Time =
Time =
Time = 3 Hours
Conclusion: Ravi take 3 hours to each office while walking
Raj travels 360 km on three fifths of his petrol tank. How far would he travel at the same rate with a full tank of petrol?
Given:
360 km can be traveled by th of petrol tank
Formula Used\Theory:
Multiplying opposite ratio with given specific value gives
Total amount value
Let the km driven from full tank be X
Then;
If of petrol tank travels 360km
And full tank travel X km
⇒ of X km is 360km
∴ × X = 360km
X = 360 × km
X = 600km
Conclusion: Full tank of petrol drives 600 km
Kajol has ₹ 75. This is of the amount she earned. How much did she earn?
Given:
of amount earned is Rs.75
Formula Used\Theory:
Multiplying opposite ratio with given specific value gives
Total amount value
Let the total amount earned by Kajol be X
Then;
If of her earnings is Rs.75
And the complete earning is Rs.X
⇒ of Rs.X is Rs.75
∴ × X = Rs.75
X = Rs.75 ×
X = Rs.200
Conclusion: Kajol earns Rs.200
It takes 17 full specific type of trees to make one tonne of paper. If there are 221 such trees in a forest, then
(i) what fraction of forest will be used to make;
A. 5 tonnes of paper.
B. 10 tonnes of paper.
(ii) To save part of the forest how much of paper we have to save.
Given:
Total 221 trees in forest
17 trees require to make 1 tonne of paper
Formula Used\Theory:
Dividing total amount by amount of 1 item gives
Number of items
(i) (A) 5 tonnes of paper
17 trees require to make 1 tonne of paper
Then;
5 tonnes of paper require
17 × 5 trees
= 85trees
Fraction of forest =
Fraction of forest =
(B) 10 tonnes of paper
17 trees require to make 1 tonne of paper
Then;
10 tonnes of paper require
17 × 10 trees
= 170trees
Fraction of forest =
Fraction of forest =
(ii) To save part of forest
Means;
× 221 trees to be saved
= 7 × 17
= 119trees to be saved
If 17 trees require to make 1 tonne of paper
Then;
Number of tonnes of paper to be saved =
= 7 tonnes
∴ 7 tonnes of paper are require to save part of forest
Simplify and write the result in decimal form :
Given:
Formula Used\Theory:
Calculation follows BODMAS rule
Bracket Of Division Multiplication Addition Subtraction
In the given calculation
Moving to the 1st bracket
⇒
=
Moving to the 2nd bracket
⇒
= ⇒
=
Moving to the 3rd bracket
⇒
= ⇒
=
∴
= = 5.18
Conclusion: The value of given calculation is 5.18
Some pictures (a) to (f) are given below. Tell which of them show:
1. 2.
3. 4.
5. 6.
(a)
(b)
(c)
(d)
(e)
(f)
(1) 2 ×
=
Figure D supports above equation
(2) 2 ×
=
Figure F supports above equation
(3) 2 ×
=
Figure C supports above equation
(4) 4 × = 1
=
Figure B supports above equation
(5) 3 ×
Figure A supports above equation
(6) 3 ×
Figure E supports above equation
Evaluate : (0.3) × (0.3) – (0.2) × (0.2)
Given:
(0.3) × (0.3) – (0.2) × (0.2)
Formula Used\Theory:
Calculation follows BODMAS rule
Bracket Of Division Multiplication Addition Subtraction
⇒ (0.3) × (0.3) – (0.2) × (0.2)
⇒ (0.3 × 0.3)-(0.2 × 0.2)
⇒ 0.09 – 0.04
⇒ 0.05
Conclusion: Result of above calculation is 0.05
Evaluate
Given:
Formula Used\Theory:
Calculation follows BODMAS rule
Bracket Of Division Multiplication Addition Subtraction
As we move to 1st part
⇒ As we remove decimal from numerator and denominator
We have to multiply 10 both on numerator and denominator
= 2
As we move to other part
⇒ As we remove decimal from numerator and denominator
We have to multiply 10 on numerator and 100 on denominator
= = 0.4
Now as per equation above
2 + 0.4
2.4
Conclusion: Result of above calculation is 2.4
Find the value of :
Given:
Formula Used\Theory:
Calculation follows BODMAS rule
Bracket Of Division Multiplication Addition Subtraction
Moving on to 1st bracket
(0.2 × 0.14)
= 0.028
Moving on to 2nd bracket
(0.5 × 0.91)
= 0.455
Moving on to the 3rd bracket
(0.1 × 0.2)
= 0.02
Now as per equation above
=
⇒ As we remove decimal from numerator and denominator
We have to multiply 100 in numerator and 1000 in denominator
= =
= 24.15
Conclusion: The result of above calculation is 24.15
A square and an equilateral triangle have a side in common. If side of triangle is cm long, find the perimeter of figure formed (Fig. 2.8).
Given:
Square BCDE and an equilateral triangle ABC have a common side BC
Side of triangle is cm
Formula Used\Theory:
All sides of square are equal
All sides of equilateral triangle are equal
If side of triangle is cm
Then;
AB = BC = CA = cm
∴ In square BCDE
If BC = cm ∵ BC is common in both triangle and square
As all sides of square are equal
BC = CD = DE = EB = cm
∴ All sides of equilateral triangle and square are equal
By joining triangle and square as in figure above
It forms a pentagon ABDEC
With sides AB = BD = DE = EC = CA = cm
⇒ Perimeter of ABDEC = AB + BD + DE + EC + CA
=
= 5 × cm
= cm
Conclusion: Perimeter of above figure is cm
Rita has bought a carpet of size 4 m × m. But her room size is What fraction of area should be cut off to fit wall to wall carpet into the room?
Given:
Size of carpet 4 m × m
Room size is
Formula Used\Theory:
Fraction of specific part means Division of specific part with
Total amount
Area of carpet = 4m × m
= 4m × m
= 4m × m
= m2
Area of room =
=
=
= m2
∴ Area need to be cut out is = Area of carpet – Area of room
= m2
= m2
= m2
= m2
Fraction of area cut out is
=
=
Conclusion: part of carpet should be cut out to fit into the room
Family photograph has length cm and breadth cm. It has border of uniform width cm. Find the area of framed photograph.
Given:
Family photograph has length cm and breadth cm
Framed border of uniform width cm.
Formula Used\Theory:
Border is added twice in both length and breadth
In order to require length and breadth of whole frame
Length of frame = length of picture + 2 × width of border
= + 2 × cm
= cm + 2 × cm
= cm + cm
= cm = cm
Breadth of frame = breadth of picture + 2 × width of border
= + 2 × cm
= cm + 2 × cm
= cm + cm
= cm = cm
Area of framed picture = cm × cm
= cm2
= 305.76cm2
Conclusion: Area of framed picture is 305.76cm2
Cost of a burger is ₹ and of Macpuff is ₹ Find the cost of 4 burgers and 14 macpuffs.
Given:
Cost of burger = Rs.
Cost of Macpuff = Rs.
Formula Used\Theory:
Cost of items = number of items × Cost of 1 item
Cost of 4 burgers =
= 4 × Rs.
= Rs.4 ×
= Rs.4 ×
= Rs.83
Cost of 14 macpuffs =
= 14 × Rs.
= Rs.14 ×
= Rs.14 ×
= Rs.217
Conclusion: Cost of 4 burgers is Rs.83 and 14 macpuffs is Rs.217
A hill, m in height, has th of its height under water. What is the height of the hill visible above the water?
Given:
A hill, m in height
th of its height is under water
Formula Used\Theory:
Difference of fraction from 1 gives value of other part
If th of its height is under water
Then;
Height of above water =
1 -
=
= th part of hill is above water
If height of hill is m
Then height of hill above water = th ×
=
=
= = 76
Conclusion: Height of hill above water is 76m
Sports: Reaction time measures how quickly a runner reacts to the starter pistol. In the 100 m dash at the 2004 Olympic Games, Lauryn Williams had a reaction time of 0.214 second. Her total race time, including reaction time, was 11.03 seconds. How long did it take her to run the actual distance?
Given:
Lauryn Williams had a reaction time of 0.214 second
Her total race of 100m time was 11.03 seconds
Formula Used\Theory:
Subtracting reaction time from total time gives
Actual time to cover the distance
Total race time of Lauryn Williams was 11.03seconds
The reaction time of Lauryn Williams was 0.214 seconds
Actual time taken to run 100m = 11.03-0.214seconds
= 10.816 seconds
Conclusion: Actual time taken to run 100m by Lauryn Williams is
10.816 seconds
State whether the answer is greater than 1 or less than 1. Put a ‘√’ mark in appropriate box.
(i)
= = 1.33
(ii)
= = 0.33
(iii)
= = 24
(iv)
= = 0.4
(v)
=
=
= = 1.857
(vi)
= = 5.66
There are four containers that are arranged in the ascending order of their heights. If the height of the smallest container given in the figure is expressed as Find the height of the largest container.
Given:
Height of smallest container is 10.5cm
Height of largest container is Xcm
Relation between smallest and largest height ⇒
× X = 10.5cm
As in the given relation × X = 10.5cm
7 × X = 10.5cm × 25
X =
To remove the decimal multiply 10 in denominator
X =
X = = 37.5cm
Conclusion: Height of largest container is 37.5cm
Replace ‘?’ with appropriate fraction.
As we move from 1st term to 2nd the ratio comes to be
=
As we move from 2nd term to 3rd the ratio comes to be
=
As we move from 3rd term to 4th the ratio comes to be
=
∴ The next upcoming term will be in same ratio as above
X =
=
Replace ‘?’ with appropriate fraction.
As we move from 1st term to 2nd the ratio comes to be
= 2
As we move from 2nd term to 3rd the ratio comes to be
= 2
As we move from 3rd term to 4th the ratio comes to be
= 2
∴ The next upcoming term will be in same ratio as above
X = 2 ×
=
Replace ‘?’ with appropriate fraction.
As we move from 1st term to 2nd the ratio comes to be
= 10
As we move from 2nd term to 3rd the ratio comes to be
= 10
As we move from 3rd term to 4th the ratio comes to be
= 10
∴ The next upcoming term will be in same ratio as above
X = 10 × 50
= 500
Replace ‘?’ with appropriate fraction.
As we move from 1st term to 2nd the ratio comes to be
=
As we move from 2nd term to 3rd the ratio comes to be
=
As we move from 3rd term to 4th the ratio comes to be
=
∴ The next upcoming term will be in same ratio as above
X = × 0.0001
= 0.00001
A student compared and –0.3. He changed to the decimal –0.25 and wrote, “Since 0.3 is greater than 0.25, –0.3 is greater than –0.25”. What was the student’s error?
As we can see that
0.3 value is greater than 0.25
∵ They are positive values
As we move to negative numeral system
Negative sign makes value smaller
Moving from 0 to -∞ we gets decreasing order of values
∴ more the value to the negative sign less it counts
And less the value to negative sign more it counts
As 0.3 value is greater than 0.25
But due to negative sign
-0.3 gets smaller than -0.25
∴ Student error was –0.3 is greater than –0.25
Instead he has to write –0.3 is smaller than –0.25
A student multiplied two mixed fractions in the following manner:
What error the student has done?
The student multiplication was:-
=
= (3 × 2)
= 6() =
The actual multiplication is :-
We have to 1st open full term only then we have to multiply
=
=
=
=
∴ The student error was multiplying terms simply with opening the complete terms.
In the pattern which fraction makes the sum greater than 1 (first time)? Explain.
By making sum of 1st 3 terms
We get;
=
Which is not greater than 1
By making sum of 1st 4 terms
We get;
=
Which is not greater than 1
By making sum of 1st 5 terms
=
=
The fraction comes to greater than 1
∴ the fraction firstly makes the sum greater than 1