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Simple and Compound Interest ( 16 to 20 ):
APTITUDE QUESTIONS (SIMPLE AND COMPOUND INTEREST):
16. At what rate of percent of simple interest will a sum of money double itself in 12 years?
A) 17/2 %
B) 19/2%
C) 13/4%
D) 25/3%
E) None of these
View Answer
Answer: option (D)
Explanation:
Let sum = x. Then, S.I. = x
R = (100 * S.I. / T * P)
Therefore, R = (100 * x / 12 * x) = 25/3%
17. If a sum of money at simple interest doubles in 6 years, it will become 4 times in?
A) 18 years
B) 16 years
C) 14 years
D) 12 years
E) None of these
View Answer
Answer: option (A)
Explanation:
Let sum = x. the, S.I. = x
Therefore, R = (100 * x / 6 * x) = 50/3%
Now, sum = x, S.I. = 3x, R = 50/3%
T = 100 * 3x/ x* 50/3 = 18 years
18. There is 50% increase in an amount in 5 years at simple interest. What will be the compound interest of Rs.15000 after 3 years at the same rate?
A) Rs.4965
B) Rs.2160
C) Rs.3972
D) Rs.6340
E) None of these
View Answer
Answer: option (A)
Explanation:
Let P = 100. Then, S.I. = Rs.50 and T = 5years
Therefore, R = 100 * 50 / 100 * 5 = 10%
Now, P = Rs.15000, T = 3 years, R = 10%
Therefore, C.I. = Rs. [15000 * {(1 + 10/100)3 – 1}] = Rs. (15000 * 331/1000) = Rs.4965
19. A sum of money invested at compound interest amounts to Rs.4624 in 2 years and to Rs.4913 in 3 years. The sum of money is?
A) Rs.4096
B) Rs.4260
C) Rs.4335
D) Rs.4360
E) None of these
View Answer
Answer: option (A)
Explanation:
S.I. on Rs.4624 for 1 year = Rs. (4913 – 4624) = Rs.289
Therefore, Rate = (100 * 289 / 4624 * 1) = 25/4%
Now, x (1 + 25/4 * 100)2 = 4624 or x * 17/16 * 17/16 = 4624
Therefore, x = (4624 * 16/17 * 16/17) = Rs.4096
20. At what rate of percent per annum will the simple interest on a sum of money be 2/5 of the amount in 10 years?
A) 6%
B) 17/3%
C) 4%
D) 20/3%
E) None of these
View Answer
Answer: option (C)
Explanation:
Let sum = x. Then, S.I. = 2x/5, T = 10 years
Therefore, R = (100 * 2x / x * 5 * 10) = 4%