Quantitative Aptitude: Simple/Compound Interest Set 23

1. A sum of rs.P invested on compound interest annually at certain rate of interest and it three times itself in five years. In how many years the amount to 9 times itself at the same rate of interest ?
5 years
8 years
7 years
10 years
12 years
Option D
3P = P(1 + R/100)^5
3 = (1 + R/100)^5
3^2 = (1 + R/100)5*2
9 = (1 + R/100)^10
time = 10 years

2. A lends rs. 5500 to B at 20% per annum and B lends the same sum to C at 22% per annum. Find the gain of B after 2 years in simple interest.
380
275
220
440
554
Option C
B gives the interest to A after 2 years,
5500 * 20/100 * 2 = 2200
C gives the interest to B after 2 years
5500 * 22/100 * 2 = 2420
the gain of B = 2420 – 2200 = 220

3. Difference between compound interest and simple interest on sum of rs.4800 at certain rate of interest after 2 years is rs. 108. What is the rate of interest ?
14%
15%
17%
12.5%
24%
Option B
CI – SI = PR^2/100^2
108 = 4800R^2/10000
R^2 = 108 * 10000/4800
P^2 = 225
R = 15%

4. After two years ratio between simple interest to principle is 2 : 5. If difference between CI and SI after two years is 208, then find principle ?
4800
4750
4540
4850
5200
Option E
Let principle = 5x
and SI = 2x
rate of interest for two years = 2x/5x * 100 = 40%
rate of interest for 1 years = 40%/2 = 20%
CI – SI = PR^2/100^2
208 = P (20)^2/10000
P = 5200

5. Two persons P and Q invested rs. (x + 3400) and (x+ 2200) at the rate of 15% and 20% respectively for two years in simple interest. After two years total SI is rs.7220, then how much amount invested by Q ?
7600
9820
5840
6450
9240
Option A
(x + 3400) * 15 /100 * 2 + (x + 2200) * 20/100 * 2 =7220
(x + 3400) * 3/10 + (x+2200)*2/5 = 7220
(3x + 102000/10) + (2x + 4400/5) = 7220
(3x + 10200 + 4x + 8800/10) = 7220
7x + 19000 = 72200
x = 7600

6. Total sum of rs.4740 is invested by two friends A and B in a scheme at the rate interest of 12% p.a for 4 year in SI. If interest received by B is 67.20 more than interest received by A, then find how much amount invested by A ?
2800
2300
1840
2350
none of these
Option B
A invested = x
B invested = 4740 – x
(4740 – x) 12/100 * 4 – x * 12/100 * 4 = 67.20
48/100 ( 4740 – x – x) = 6720
12/25 (4740 – 2x) = 67.20
4740 – 2x = 67.20 * 25/12
4740 – 2x = 140
2x = 4600
x = 2300
amount invests by A= 2300

7. What is the compound interest accrued on a sum of 1400 at the rate of 6% in 2 years ?
184.25
254.08
334.05
173.04
234.14
Option D
Compound interest for 2 years
6 + 6 + 6 * 6/100 = 12.36 %
compound interest = 1400 * 12.36/100 = 173.04

8. The compound interest on a certain sum at 20% p.a for 2 years is rs. 98 more than the simple interest on same sum at 15% per annum for 2 years. What is the sum ?
700
480
320
1000
650
Option A
Let sum is rs.x
compound interest for 2 years at 20 % p.a
20 + 20 + 20 * 20 /100 = 44%
simple interest for 2 years at 15 % = 15% * 2 = 30%
x * 44/100 – x * 30/100 = 98
x = 700

9. A certain sum is deposited at rate of 40% p.a on Compound interest. Difference between interest earned at the 1st and 2nd year is rs.384. What is the sum ?
4800
4500
3200
4500
2400
Option E
Let sum = 100x
interest of 1st year = 100x * 40/100 = 40x
total amount at the end of the 1st year = 100x + 40x = 140x
interest of 2nd year = 140x * 40/100 = 56x
difference = 56x – 40x = 16x
16x = 384
x = 24
sum = 100x = 100 * 24 = 2400

10. What is difference between the compound interest on rs.4000 for 1.5 years at 40% p.a compounded yearly and half-yearly ?
182
192
534
314
208
Option B
Rate of interest after 1.5 years compounded yearly at 40%p.a
40 + 20 + 800/100 = 68%
CI = 4000 * 68/100 = 2720
Rate of interest after 1.5 years compounded half-yearly
rate of interest = 40/2 = 20%
20 + 20 + 20 * 20 /100 = 44%
44% + 20% + 880/100 = 72.80%
CI = 4000 * 72.80 /100 = 2912
difference = 2912 – 2720 = 192