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Simple and Compound Interest ( 21 to 25 ):
APTITUDE QUESTIONS (SIMPLE AND COMPOUND INTEREST):
21. How long will it take a sum of money invested at 5% p.a. S.I. to increase its value by 40%?
A) 5 years
B) 6 years
C) 7 years
D) 8 years
E) None of these
View Answer
Answer: option (D)
Explanation:
Let the sum be x. Then, S.I. = 40% of x = 2x/5, R = 5%
Therefore, T = (100 * 2x/5 * 1/ x * 5) = 8 years.
22. How much annual payment will be discharge on a debt of Rs.4410 due in 3 years at 5% simple interest?
A) Rs.1600
B) Rs.1500
C) Rs.1400
D) Rs.1550
E) None of these
View Answer
Answer: option (C)
Explanation:
Let the annual installment be Rs. X. Then,
= [x + (x * 2 * 5 / 100)] + [x + (x * 1 * 5 / 100)] + x = 4410
- 22x/20 + 21x/20 + x = 4410
- (22x + 21x + 20x) / 20 = 4410
- 63x = 4410 * 20
- x = 4410 * 20 / 63
- x = 1400
23. A sum was put at simple interest at a certain rate for 3 years. Had it been put at 2% higher rate, it would have fetched Rs.60 more. The sum is?
A) Rs.1000
B) Rs.1500
C) Rs.1600
D) Rs.1800
E) None of these
View Answer
Answer: option (A)
Explanation:
Let the sum be Rs. X and original rate be R%. Then,
- x * (R + 2) * 3 / 100 – x * R * 3/100 = 60
- 3Rx + 6x – 3Rx = 6000
- 6x = 6000
- x = 1000
24. The time in which Rs.2000 will amount to Rs.2420 at 10% p.a. compound interest is
A) 5 years
B) 3 years
C) 4 years
D) 2 years
E) None of these
View Answer
Answer: option (D)
Explanation:
Given that, P = Rs.2000, A = Rs.2420, R = 10%
Therefore, 2420 = 2000 (1 + 10/100)n
- 121/100 = (11
- /10)n
- (11/10)2 = (11/10)n
- n = 2 years
25. A woman borrows Rs.3825 which has to be paid back by the end of 2 years in two equal yearly installments with compound interest at the rate of 4% p.a. How much will each installment be?
A) Rs.1275
B) Rs.1352
C) Rs.2028
D) Rs.2100
E) None of these
View Answer
Answer: option (C)
Explanation:
Let the value of each installment be Rs. x. Then,
(P.W. of Rs. x due 1 year hence) + (P.W. of Rs. x due 2 years hence) = Rs.3825
- x / (1 + 4/100) + x / (1 + 4/100)2 = 3825
- 25x/26 + 625x/676 = 3825
- 1275x = 3825 * 676
- x = 3825 * 676 / 1275
- x = 2028
Therefore, value of each installment = Rs.2028