Compound Interest
Class 8th Mathematics (old) MHB Solution
- Use the formula to find simple interest and amount.
- Use the formula to find simple interest and amount.
- Use the formula to find simple interest and amount.
- Use the formula to find simple interest and amount.
- Use the formula to find simple interest and amount.
- If a certain sum of money earns an interest of Rs 3,630 in 3 years at the rate…
- The simple interest on Rs 45,000 in 3 years is Rs 13,500. What is the rate of…
- What sum of money will have to be invested and for how many years, in order to…
- Use the formula to find the amount and the compound interest.
- Use the formula to find the amount and the compound interest.
- Use the formula to find the amount and the compound interest.
- Use the formula to find the amount and the compound interest.
- Use the formula to find the amount and the compound interest.
- Use the formula to find the amount and the compound interest.
- Ganesh invested Rs 50,000 in a nationalized bank for 2 years at the rate of 9…
- In order to buy a colour TV set, Altaf borrowed Rs 12,000 from a bank at a…
- Bhakti borrowed Rs 4000 from a women’s savings group to buy a sweing machine.…
- Shreya won a cash prize of Rs 1250 for standing first in the Std VII exam. She…
- Write the proper numbers in the blanks in the table below.
- Write the proper numbers in the blanks in the table below.
- Write the proper numbers in the blanks in the table below.
- |l|l|l| & & 15 , 000&10&3 Write the proper numbers in the blanks in the table…
- Write the proper numbers in the blanks in the table below.
- Write the proper numbers in the blanks in the table below.
- Sunitabi borrowed Rs 60,000 at 9 p.c.p.a. simple interest for 3 years to have…
- Ambadas took a loan of Rs 96,000 at compound interest from a bank to drill a…
- The population of a village is 1,20,000. If the population increases by 5%…
- Two years ago Rajani purchased a machine for Rs 75,000. If its value falls by…
- A wholesale trader sold Rs 20 crore worth of cloth this year. If the sale of…
- A car is valued at Rs 4,00,000. If its value falls at 2.5% per year, what will…
Exercise 63
Question 1.Use the formula to find simple interest and amount.
Answer:
Given: Principal (P) = Rs. 9000, Rate of Interest (R) = 10% and Number of years (T) = 3year
As simple interest (SI):
⇒ SI = Rs. 2700
As we know,
Amount = P + SI
A = 9000 + 2700
⇒ A = Rs.11700
Question 2.
Use the formula to find simple interest and amount.
Answer:
Given: Principal (P) = Rs. 15000,
Rate of Interest (R) = 11% and
Number of years (T) = 2year
As simple interest (SI):
⇒ SI = Rs. 3300
As we know,
Amount = P + SI
A = 15000 + 3300
⇒ A = Rs.18300
Question 3.
Use the formula to find simple interest and amount.
Answer:
Given: Principal (P) = Rs. 50000, Rate of Interest (R) = 9% and Number of years (T) = 4year
As simple interest (SI):
⇒ SI = Rs. 18000
As we know,
Amount = P + SI
A = 50000 + 18000
⇒ A = Rs.68000
Question 4.
Use the formula to find simple interest and amount.
Answer:
Given: Principal (P) = Rs. 1,25,000, Rate of Interest (R) = 12% and Number of years (T) = 2year
As simple interest (SI):
⇒ SI = Rs. 30000
As we know,
Amount = P + SI
A = 125000 + 30000
⇒ A = Rs.155000
Question 5.
Use the formula to find simple interest and amount.
Answer:
Given: Principal (P) = Rs. 1,50,000, Rate of Interest (R) = 10% and Number of years (T) = 3year
As simple interest (SI):
⇒ SI = Rs. 45000
As we know,
Amount = P + SI
A = 150000 + 45000
⇒ A = Rs.195000
Question 6.
If a certain sum of money earns an interest of Rs 3,630 in 3 years at the rate of 11 p.c.p.a, what was the principal?
Answer:
Given: simple interest (SI):= Rs. 3630, Rate of Interest (R) = 11% and Number of years (T) = 3year, Principal (P) = ?
As simple interest (SI):
⇒ 363000 = 33P
⇒ P = 11000
Principal (P) = Rs. 11000
Question 7.
The simple interest on Rs 45,000 in 3 years is Rs 13,500. What is the rate of interest?
Answer:
Given: simple interest (SI):= Rs. 13,500, Rate of Interest (R) = ?% and Number of years (T) = 3 year, Principal (P) = Rs.45,000
As simple interest (SI):
⇒ 13500 = 1350R
⇒ R = 10
Rate of Interest (R) = 10%
Question 8.
What sum of money will have to be invested and for how many years, in order to get simple interest of Rs 10,000 at the rate of 10 p.c.p.a.? (Write three pairs of values for P and N.)
Answer:
Given: simple interest (SI):= Rs. 10,000, Rate of Interest (R) = 10% and Number of years (T) = ?, Principal (P) = ?
As simple interest (SI):
⇒ PT = 100000
Now,
(i) If P = 50000 then T = 2year
(ii) If P = 20000 then T = 5year
(iii) If P = 10000 then T = 10year
Exercise 64
Question 1.Use the formula to find the amount and the compound interest.
Answer:
Given: Principal (P) = Rs. 8000, Rate of Interest (R) = 10% and Number of years (n) = 2year
As Amount (A):
⇒ A = Rs. 9680
As compound interest (CI),
CI = A - P
CI = 9680 - 8000
⇒ CI = Rs.1680
Question 2.
Use the formula to find the amount and the compound interest.
Answer:
Given: Principal (P) = Rs. 6400, Rate of Interest (R) = 12.5% and Number of years (n) = 2year
As Amount (A):
⇒ A = Rs. 8100
As compound interest (CI),
CI = A - P
CI = 8100 - 6400
⇒ CI = Rs.1700
Question 3.
Use the formula to find the amount and the compound interest.
Answer:
Given: Principal (P) = Rs. 10000, Rate of Interest (R) = 10% and Number of years (n) = 2year
As Amount (A):
⇒ A = Rs. 12100
As compound interest (CI),
CI = A - P
CI = 12100 – 10000
⇒ CI = Rs.2100
Question 4.
Use the formula to find the amount and the compound interest.
Answer:
Given: Principal (P) = Rs. 15000, Rate of Interest (R) = 10% and Number of years (n) = 3year
As Amount (A):
⇒ A = Rs. 19965
As compound interest (CI),
CI = A - P
CI = 19965 - 15000
⇒ CI = Rs.4965
Question 5.
Use the formula to find the amount and the compound interest.
Answer:
Given: Principal (P) = Rs. 20000, Rate of Interest (R) = 5% and Number of years (n) = 3year
As Amount (A):
.
⇒ A = Rs. 23152.50
compound interest (CI),
CI = A - P
CI = 23152.50 - 20000
⇒ CI = Rs.3152.50
Question 6.
Use the formula to find the amount and the compound interest.
Answer:
Given: Principal (P) = Rs. 16000, Rate of Interest (R) = 
and Number of years (n) = 3year
As Amount (A):
⇒ A = Rs. 22781.25
As compound interest (CI),
CI = A - P
CI = 22781.25 - 16000
⇒ CI = Rs.6781.25
Question 7.
Ganesh invested Rs 50,000 in a nationalized bank for 2 years at the rate of 9 p.c.p.a at compound interest. What amount will Ganesh receive from the bank at the end of 2 years?
Answer:
Given: Principal (P) = Rs. 50,000, Rate of Interest (R) = 9% and Number of years (n) = 2year
As Amount (A):
⇒ A = Rs. 59,405
Amount received by Ganesh from bank in 2 year = Rs 59,405.
Question 8.
In order to buy a colour TV set, Altaf borrowed Rs 12,000 from a bank at a compound rate of interest of 10 p.c.p.a. for 2 years. What is the amount that Altaf must pay bank to the bank at the end of 2 years?
Answer:
Given: Principal (P) = Rs. 12,000, Rate of Interest (R) = 10% and Number of years (n) = 2year
As Amount (A):
⇒ A = Rs. 14520
Amount that atlaf must to bank at the end 2year = Rs 14520.
Question 9.
Bhakti borrowed Rs 4000 from a women’s savings group to buy a sweing machine. If the rate of compound interest is 5 p.c.p.a., what amount will she have to return at the end of 3 years?
Answer:
Given: Principal (P) = Rs. 4,000, Rate of Interest (R) = 5% and Number of years (n) = 3year
As Amount (A):
⇒ A = Rs. 4630.50
Amount bhakti have to pay to the bank in 3 year = Rs 4630.50.
Question 10.
Shreya won a cash prize of Rs 1250 for standing first in the Std VII exam. She invested that amount as a term deposit in a bank for 3 years at a rate of compound interest of 8 p.c.p.a. What is the amount that she will receive from the bank at the end of the term?
Answer:
Given: Principal (P) = Rs. 1250, Rate of Interest (R) = 8% and Number of years (n) = 3year
As Amount (A):
⇒ A = Rs. 1574.64
Amount that shreya will receive from the bank at the end of the term = Rs. 1574.64
Exercise 65
Question 1.Write the proper numbers in the blanks in the table below.
Answer:
Given: Principal (P) = Rs. 8000, Rate of Interest (R) = 10% and Number of years (n) = 2year
As simple interest (SI):
⇒ SI = Rs. 1600
As Amount (A):
⇒ A = Rs. 9680
As compound interest (CI),
CI = A - P
CI = 9680 - 8000
⇒ CI = Rs.1680
Difference between CI and SI is :
D = CI – SI
⇒ D = 1680 – 1600
⇒ D = Rs. 80
Question 2.
Write the proper numbers in the blanks in the table below.
Answer:
Given: Principal (P) = Rs. 6400, Rate of Interest (R) = 12.5% and Number of years (n) = 2year
As simple interest (SI):
⇒ SI = Rs. 1600
As Amount (A):
⇒ A = Rs. 8100
As compound interest (CI),
CI = A - P
CI = 8100 - 6400
⇒ CI = Rs.1700
Difference between CI and SI is :
D = CI – SI
⇒ D = 1700 – 1600
⇒ D = Rs. 100
Question 3.
Write the proper numbers in the blanks in the table below.
Answer:
Given: Principal (P) = Rs. 10000, Rate of Interest (R) = 10% and Number of years (n) = 2year
As simple interest (SI):
⇒ SI = Rs. 2000
As Amount (A):
⇒ A = Rs. 12100
As compound interest (CI),
CI = A - P
CI = 12100 – 10000
⇒ CI = Rs.2100
Difference between CI and SI is :
D = CI – SI
⇒ D = 2100 – 2000
⇒ D = Rs. 100
Question 4.
Write the proper numbers in the blanks in the table below.
Answer:
Given: Principal (P) = Rs. 15000, Rate of Interest (R) = 10% and Number of years (n) = 3year
As simple interest (SI):
⇒ SI = Rs. 4500
As Amount (A):
⇒ A = Rs. 19965
As compound interest (CI),
CI = A - P
CI = 19965 - 15000
⇒ CI = Rs.4965
Difference between CI and SI is :
D = CI – SI
⇒ D = 4965 – 4500
⇒ D = Rs. 465
Question 5.
Write the proper numbers in the blanks in the table below.
Answer:
Given: Principal (P) = Rs. 20000, Rate of Interest (R) = 5% and Number of years (n) = 3year
As simple interest (SI):
⇒ SI = Rs. 3000
As Amount (A):
⇒ A = Rs. 23152.50
As compound interest (CI),
CI = A - P
CI = 23152.50 - 20000
⇒ CI = Rs.3152.50
Difference between CI and SI is :
D = CI – SI
⇒ D = 3152.50 – 3000
⇒ D = Rs. 152.50
Question 6.
Write the proper numbers in the blanks in the table below.
Answer:
Given: Principal (P) = Rs. 16000, Rate of Interest (R) = 
and Number of years (n) = 3year
As simple interest (SI):
⇒ SI = Rs. 6000
As Amount (A):
⇒ A = Rs. 22781.25
As compound interest (CI),
CI = A - P
CI = 22781.25 - 16000
⇒ CI = Rs.6781.25
Difference between CI and SI is :
D = CI – SI
⇒ D = 6781.25 – 6000
⇒ D = Rs. 781.25
Question 7.
Sunitabi borrowed Rs 60,000 at 9 p.c.p.a. simple interest for 3 years to have her house repaired. Had she borrowed the same sum for the same period and the same rate at compound interest, how much more interest would she have had to pay?
Answer:
Given: Principal (P) = Rs. 60000, Rate of Interest (R) = 9% and Number of years (n) = 3year
As simple interest (SI):
⇒ SI = Rs. 16200
For compound interest:
As Amount (A):
⇒ A = Rs. 77701.7
As compound interest (CI),
CI = A - P
CI = 77701.7 - 60000
⇒ CI = Rs.17701.74
Difference between CI and SI is :
D = CI – SI
⇒ D = 17701.74 – 16200
⇒ D = Rs. 1501.74
The more interest would sunitabi have had to pay = Rs.1501.74
Question 8.
Ambadas took a loan of Rs 96,000 at compound interest from a bank to drill a well in his field. If the rate is 6.25 p.c.p.a. what amount will he have to pay to the bank, if he returns the loan after 2 years, what amount will he have saved had he been able to borrow the same amount at simple interest for the same period at the same rate?
Answer:
Given: Principal (P) = Rs. 96000, Rate of Interest (R) = 6.25% and Number of years (n) = 2year
As simple interest (SI):
⇒ SI = Rs. 12000
For compound interest:
As Amount (A):
⇒ A = Rs. 108,375
As compound interest (CI),
CI = A - P
CI = 108375 - 96000
⇒ CI = Rs.12375
Difference between CI and SI is :
D = CI – SI
⇒ D = 12375 – 12000
⇒ D = Rs. 375
She would save amount = Rs. 375
Exercise 66
Question 1.The population of a village is 1,20,000. If the population increases by 5% every year, what will it be after 3 years?
Answer:
Given: Principal (P) = Initial population = Rs. 1,20,000, Rate of Interest (R) =rate of growth = 5% and Number of years (n) = 3year
As Amount (A) = Population after two years:
⇒ A = 138915
Population after 3 years will be = 138915
Question 2.
Two years ago Rajani purchased a machine for Rs 75,000. If its value falls by 4% every year, what is the value of the machine today?
Answer:
Given: Principal (P) = Initial cost of machine = Rs. 75,000, Rate of Interest (R) = fall in rate = 4% and Number of years (n) = 2year
As Amount (A) = Population after two years:
(it is case of fall hence negative)
⇒ A = 69120
Rate of machine after 2 years will be = Rs 69120
Question 3.
A wholesale trader sold Rs 20 crore worth of cloth this year. If the sale of cloth increases at a rate of 2% per year, how much will the sale be after three years?
Answer:
Given: Principal (P) = Initial sale of cloth = Rs. 20,00,000,00, Rate of Interest (R) =increase in sale = 2% and Number of years (n) = 3year
As Amount (A) = Population after two years:
⇒ A = 21,22,41,600
Sale of cloth after 3 years will be = 21,22,41,600
Question 4.
A car is valued at Rs 4,00,000. If its value falls at 2.5% per year, what will its value be after 3 years?
Answer:
Given: Principal (P) = Initial price of car = Rs.4,00,000, Rate of Interest (R) = fall in rate = 2.5% and Number of years (n) = 3year
As Amount (A) = Population after two years:
(it is case of fall hence negative)
⇒ A = Rs 370743.75
Rate of car after 3 years will be = Rs 370743.75