Compound Interest problems
- 1. At a certain rate of interest the compound interest of 3 years and simple interest of 5 years for certain sum of money is respectively Rs. 1513.2 and Rs. 2400. Find the common rate of interest per annum ?
Options- A. 5%
- B. 6%
- C. 4%
- D. 3% Discuss
Correct Answer: 5%
Explanation:
Given compound interest for 3 years = Rs. 1513.2
and simple interest for 5 years = Rs. 2400
Now, we know that C.I =
=> 1513.2 = ...........(A)
And S.I = PTR/100
=> 2400 = P5R/100 ..................(B)
By solving (A) & (B), we get
R = 5%.
- 2. What will be the compound interest on a sum of Rs.25,000 after 3 years at the rate of 12 p.c.p.a?
Options- A. Rs.10123.20
- B. Rs.12100
- C. Rs.12552
- D. Rs.12665 Discuss
Correct Answer: Rs.10123.20
Explanation:
Amount
= Rs.(25000x(1+12/100)³
= Rs.(25000x28/25x28/25x28/25)
= Rs. 35123.20.
C.I = Rs(35123.20 -25000)
= Rs.10123.20
- 3. Rs. 5887 is divided between Shyam and Ram, such that Shyam's share at the end of 9 years is equal to Ram's share at the end of 11 years, compounded annually at the rate of 5%. Find the share of Shyam.
Options- A. 3567
- B. 3452
- C. 3087
- D. 3544 Discuss
Correct Answer: 3087
Explanation:
Shyam's share * (1+0.05)9 = Ram's share * (1 + 0.05)11
Shyam's share / Ram's share = (1 + 0.05)11 / (1+ 0.05)9 = (1+ 0.05)2 = 441/400
Therefore Shyam's share = (441/841) * 5887 = 3087
- 4. The difference between the compound interest and simple interest on a certain sum at 10% per annum for 2 years is Rs. 631. Find the sum.
Options- A. 60100
- B. 61100
- C. 62100
- D. 63100 Discuss
Correct Answer: 63100
Explanation:
Let the sum be Rs. x. Then,
C.I. = x ( 1 + ( 10 /100 ))^2 - x = 21x / 100 ,
S.I. = (( x * 10 * 2) / 100) = x / 5
(C.I) - (S.I) = ((21x / 100 ) - (x / 5 )) = x / 100
( x / 100 ) = 632 * x = 63100.
Hence, the sum is Rs.63,100.
- 5. The difference between the compound interest and simple interest on a certain sum at 10% per annum for 2 years is Rs. 631. Find the sum.
Options- A. 60100
- B. 61100
- C. 62100
- D. 63100 Discuss
Correct Answer: 63100
Explanation:
Let the sum be Rs. x. Then,
C.I. = x ( 1 + ( 10 /100 ))^2 - x = 21x / 100 ,
S.I. = (( x * 10 * 2) / 100) = x / 5
(C.I) - (S.I) = ((21x / 100 ) - (x / 5 )) = x / 100
( x / 100 ) = 632 * x = 63100.
Hence, the sum is Rs.63,100.
- 6. Rs 1000 is being charged at 50% per annum. what is the interest for 3rd year at compound interest?
Options- A. 1122
- B. 1025
- C. 1125
- D. 625 Discuss
Correct Answer: 1125
Explanation:
Total amount for two years =
Now , interest for third year =
- 7. The minimum number of half years in which a sum of money kept at 60% compound interest will be quadrupled is ?
Options- A. 2
- B. 4
- C. 3
- D. 6 Discuss
Correct Answer: 6
Explanation:
Let us assume Amount be 100 Rs and we calculate in CI
First year 60% of 100 = 60 amount (100+60) is 160
Second year 60% of 160 = 96 amount (160+96) is 256
Third year 60% of 256 =153.6 amount (256+153.6) is 409.6
Here the Amount of 100 Rs is quadrapled in 3 years.
One year contains 2 half years
Three year has 6 half years.
Therefore, It takes 6 half years.
- 8. A sum of money invested at compound interest amounts to Rs. 800 in 3 years and to Rs. 840 in 4 years. The rate of interest per annum is
Options- A. 6%
- B. 4%
- C. 5%
- D. 7% Discuss
Correct Answer: 5%
Explanation:
S.I. on Rs.800 for 1 year
=Rs[840 - 800]
= Rs.40
Rate
=(100x40/800x1)%
= 5%
- 9. What is the SI on Rs.2500/- at the rate of 12% per annum for 8 years?
Options- A. 2200
- B. 2300
- C. 2400
- D. 2500 Discuss
Correct Answer: 2400
Explanation:
S.I=PNR/100
- 10. Find the compound interest on Rs. 2680 at 8% per annum for 2 years ?
Options- A. Rs. 664.21
- B. Rs. 548.68
- C. Rs. 445.95
- D. Rs. 692.57 Discuss
Correct Answer: Rs. 445.95
Explanation:
We know Compound Interest = C.I. = P1+r100t - 1
Here P = 2680, r = 8 and t = 2
C.I. = 26801 + 81002-1= 268027252-12= 26802725+12725-1= 2680 5225×225
= (2680 x 52 x 2)/625
= 445.95
Compound Interest = Rs. 445.95
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