Problems on Simple Interest
Q11. Find S.I on Rs. 16250 at 6% p.a. for 73 days
(a) 173
(b) 195
(c) 220
(d) 237
Answer: (b) 195
P = Rs. 16250 r = 6% t = 73 days = 73/365 year = 1/5 year
∴ S.I = | P X r X t | = | 16250 X 6 X 1/5 |
100 | 100 |
= | 16250 X 6 X 1 | = Rs. 195 |
100 X 5 |
Find S.I on Rs. 5400 at 5 | 2 | % p.a for 6 months |
3 |
(a) 153
(b) 165
(c) 193
(d) 201
Answer: (a) 153
P = Rs. 5400
r = 5 | 2 | % = | 17 | % |
3 | 3 |
t = 6 months = 6/12 year = 1/2 year
S.I = | P X r X t | = | 5400 X (17/3) X (1/2) |
100 | 100 |
= 54 X | 17 | X | 1 | = 153 |
3 | 2 |
Q13. A sum when reckoned at 10% S.I amounts to Rs. 2400 in 4 years. Find the sum.
(a) 1575.75
(b) 1610.30
(c) 1612.50
(d) 1714.30
Answer: (d) 1714.30
Let the sum be Rs. x
∴ S.I = | x X 10 X 4 | = | 4x |
100 | 10 |
∴ Amount = Rs ( x + | 4x | ) = Rs. | 14x |
10 | 10 |
A/Q | 14x | = 2400 |
10 |
⇒ x = | 2400 X 10 | = Rs. 1714.30 |
14 |
Q14. A certain sum is invested on simple interest. If it trebles in 5 years, what is the rate of interest ?
(a) 25 %
(b) 35 %
(c) 40 %
(d) 50 %
Answer: (c) 40 %
Let the sum be Rs. x
∴ Amount = Rs. 3x
∴ S.I = Rs (3x -x) = Rs. 2x
Now r = | S.I X 100 | = | 2x X 100 | = 40 % |
P X t | x X 5 |
Q15. In how many years, a sum will be thrice of it at the rate of 10% per annum ?
(a) 8 years
(b) 10 years
(c) 15 years
(d) 20 years
Answer: (d) 20 years
Let the sum be Rs. x
∴ Amount = Rs. 3x
∴ S.I = Rs (3x -x) = Rs. 2x
Now t = | S.I X 100 | = | 2x X 100 | = 20 years |
P X r | x X 10 |
Q16. A man invests 1/2 of his capital at 6% per annum, 1/3 at 9% per annum and the remainder at 10% per annum. If his annual income is Rs. 560, the capital is
(a) 6384.15
(b) 6825.75
(c) 7219.20
(d) 7304.35
Answer: (d) 7304.35
Let the capital be Rs. x
A/Q, S.I1 + S.I2 + S.I3 = 560
⇒ | x X (½) X 6 X 1 | + | x X (1/3) X 9 X 1 | + | { x - ((x/2) + (x/3)} X 10 X 1 | = 560 |
100 | 100 | 100 |
⇒ | 3x | + | 3x | + | (x/6) X 10 | = 560 |
100 | 100 | 100 |
⇒ 3x + 3x + | 5x | = 56000 |
3 |
⇒ | 18x + 5x | = 56000 |
3 |
⇒ 23x = 56000 X 3
⇒ x = Rs. 7304.35
Q17. The sum of money that will give Rs. 1 as simple interest per day at the rate of 4% per annum is
(a) 9036
(b) 9125
(c) 9810
(d) 9985
Answer: (b) 9125
1 day interest = Rs 1
∴ 365 day interest = Rs 365
∴ S.I = Rs. 365
r = 4 %
Now P = | S.I X 100 | = | 365 X 100 | = Rs. 9125 |
r X t | 4 X 1 |
Q18. The difference between the interest received from two different banks on Rs. 4000 for 2 years is Rs. 20. The difference between their rates is
(a) 0.23
(b) 0.25
(c) 0.33
(d) 0.47
Answer: (b) 0.25
Let the rates be x% and y%
Now S.I1 - S.I2 = 20
⇒ | 4000 X x X 2 | - | 4000 X y X 2 | = 20 |
100 | 100 |
⇒ 80x - 80y = 20
⇒ 80 (x - y) = 20
⇒ x - y = 20 / 80 = 0.25
Q19. A sum of Rs. 500 amounts to Rs. 620 in 4 years. What will it amount to if the rate of interest is increased by 2% ?
(a) 590
(b) 630
(c) 660
(d) 720
Answer: (c) 660
P = Rs. 500
Amount = Rs. 620
∴ S.I = Rs. (620 - 500) = Rs. 120
t = 4 years
∴ r = | S.I X 100 | = | 120 X 100 | = 6 % |
P X t | 500 X 4 |
New rate = 6% + 2% = 8%
S.I = | P X r X t | = | 500 X 8 X 4 | = 160 |
100 | 100 |
∴ Required amount = Rs. (500 + 160) = Rs. 660
Q20. The simple interest at x% per annum for x years will be Rs. x on a sum of
(a) 75/x
(b) 100/x
(c) 120/x
(d) 150/x
Answer: (b) 100/x
Let the sum be Rs. P
P = | S.I X 100 | = | x X 100 | = Rs. | 100 |
r X t | x X x | x |
Practice Test Exam