# Simple and Compound Interest ( 11 to 15 )

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Simple and Compound Interest ( 11 to 15 ):

# APTITUDE QUESTIONS (SIMPLE AND COMPOUND INTEREST):

11. At what rate of compound interest per annum will a sum of Rs.1200 become Rs.1348.32 in 2 years?

A)    7%

B)    7.5%

C)    6.5%

D)    6%

E)     None of these

Explanation:

Let the rate be R% p.a. Then,

1200 * (1 + R/100)2 = 1348.32

(1 + R/100)2 = (106/100)2 or 1 + R/100 = 106/100 or R = 6%

12. If Rs.54 amounts to Rs.70.20 in 2 years, what will Rs.66 amount to in 4 years at the same rate % p.a?

A)    80

B)    124.70

C)    127.40

D)    137.60

E)     None of these

Explanation:

P = Rs.54, S.I. = Rs. (70.20 – 54) = Rs.16.20, T = 2

So, rate = (100 * 16.20 / 54 * 2) % = 15%

Now, P = Rs.66, R = 15%, T= 4

Therefore, S.I. = Rs. (66 * 15 * 4 / 100) = Rs.39.60

13. The interest on a certain deposit at 5% p.a. is Rs.102.50 in 2 year. For the same deposit at 5.5% p.a. what will be the additional interest for 2 year?

A)    Rs.20.25

B)    Rs.10.25

C)    Rs.25

D)    Rs.42.50

E)    None of these

Explanation:

S.I. = Rs.102.50, R = 5%, T = 2 year

P = Rs. (100 * 102.50 / 5 * 2) = Rs.1025

Now, P = Rs.1025, R = 5.5%, T = 2 year

S.I. = Rs. (1025 * 5.5 * 2 / 100) = Rs.112.75

Therefore, difference in interest = Rs. (112.75 – 102.50) = Rs.10.25

14. What will be the compound interest on a sum of Rs.50000 after 3 years at the rate of 10% p.a.?

A)    Rs.9500

B)    Rs.10500

C)    Rs.16550

D)    Rs.17000

E)    None of these

Explanation:

Amount = Rs. [50000 * (1 + 10/100)3] = Rs. 50000 * 11/10 *11/10 *11/10 = Rs.66550

Therefore, C.I. = Rs. (66550 – 50000) = Rs.16550

15. The compound interest on a certain sum for 2 years at 10% per annum is Rs.546. What will be the simple interest on the same sum for double the time and at half the rate percent per annum is?

A)    Rs.400

B)    Rs.520

C)    Rs.620

D)    Rs.800

E)    None of these

Explanation:

= [P (1 + 10/100)2 – P] = 546

= P [(11/10)2 – 1] = 546

P = (546 * 100 / 21) = 2600

Therefore, Sum = Rs.2600

So, S.I. = Rs. (2600 * 5 * 4 / 100) = Rs.520