42. A sum of money double itself in 8 years at some rate of interest. In how many years would it treble itself ?
(A) 16 years .
(B) 12 years
(C) 15 years
(D) 14 years
43. A sum of amounts will be doubled in 71/2 years. What is the rate per cent ?
44. A sum amounts to Rs.1180 in 3 years and to Rs.1300 in 5 years. Find the rate of interest.
45. A certain sum amounts to Rs.17,200 at 12% simple interest per annum in a period in which Rs.22,080 amounts to Rs.37,536 at 14% simple interest per annum. Find the sum.
46. Ten copies of the book can be bought for a certain sum of money payable at the end of 2 years. 12 copies of the same book can be bought for the same sum in ready cash. What is the rate of interest per annum ?
47. Sita deposited some money in a bank at the rate of simple interest of 5.25% per annum. After 2 years, she has got Rs. 840 as interest. Let us write by calculating, the money she has deposited into the bank.
48. Let us calculate the number of years for which the interest of Rs.600 at the rate of simple interest of 8% per annum will be Rs.168.
49. At the same rate of simple interest per annum, if a principal becomes the amount of Rs.7100 in 7 years and of Rs.6200 in 4 years, let us determine the principal amount.
50. A weaver cooperative society takes a loan of Rs.15,000 for buying a power loom. After 5 years, the society has to repay Rs.22,125 for recovering the loan. Find the rate of simple interest per annum.
(A) 91/2 % p.a.
(B) 81/2 % p.a.
(C) 51/3 % p.a.
(D) 61/2 % p.a.
51. If the total interest becomes Rs..x for a principal having the rate of simple interest of x% per annum for x years then, principal will be
(A) Rs. x
(D) Rs. 100/x2
52. If a principal becomes twice of its amount in 10 years, the rate of simple interest per annum is
53. Calculate the principal whose monthly interest is Rs.1 having the rate of simple interest of 5% per annum.
54. Write the number of years in which the amount becomes twice of the principal having the rate of simple interest 61/4 % per annum.
55. The ratio of the principal and the amount (principal along with interest) in 1 year is 8 : 9, the rate of simple interest per annum is
(A) 111/2 %
(B) 121/2 %
(C) 101/2 %
(D) 131/2 %
57. Present price of a machine in Rs.2p and if price of the machine decreases by 2r% in each year, the price of machine after 2n years will be
(A) Rs. p(1−r/100)n
(B) Rs. 2p(1−r/50)n
(C) Rs. p(1−r/50)2n
(D) Rs. 2p(1−r/50)2n
58. A person deposited Rs.100 in a bank and got the amount Rs.121 for two years, the rate of compound interest per annum is
59. Find the rate of compound interest per annum, so that the amount on Rs.400 for 2 years becomes Rs.441.
60. If a sum of money doubles itself at the fixed rate of compound interest per annum in n years, find in how many years it will become four times.
61. Determine the principal amount that at the rate of 5% compound interest per annum becomes Rs.615 after two years.
62. If the rate of increase in population is r% per year, the population after n years is p : let us find the population that was n years before.
WBCS Main Question Paper – 2018
13. A small owner took a loan of Rs.73000 from his friend. He repay principal along with interest Rs.73100 after 1 day. The rate of simple interest per annum is
21. Through the publicity of road safety programmes the street accident in a state has been decreased by 10% in comparison to its previous year. In the present year if the number of street accidents be 2187, the number of street accidents that had been in the state 3 years before is
38. How much time will it take for an amount of Rs.450 to yield Rs.81 as interest at 4.5% per annum of simple interest ?
(A) 3.5 years
(B) 4 years
(C) 4.5 years
(D) 5 years
39. The compound interest on Rs.30000 at 7% per annum is Rs.4347. The period (in years) is
40. What is the difference between the compound interests on Rs.5000 for 11/2 years at 4% per annum compounded yearly and half-yearly ?
(A) Rs. 2.04
(B) Rs. 3.06
(C) Rs. 4.08
(D) Rs. 8.30
51. If the total interest becomes Rs.x for any principal having the rate of simple interest of x% per annum for x years then the principal will be
(A) Rs. x
(B) Rs. 100x
(C) Rs. 100/x
(D) Rs. 100/x2
78. Ankur invested a sum of Rs.16,800 for four years in a scheme. The rate of interest in the scheme is 8% per annum compounded yearly for the first two years and 10% for the 3rd and 4th years compounded yearly. What will be the compound interest at the end of 4 years ?
(A) Rs. 6810
(B) Rs. 6910
(C) Rs. 6540
(D) Rs. 6210
98. Present price of a machine is Rs. p and if price of the machine increases by 2r% in each year, the price of machine will be after n year —
(A) P(1 + r/100)n
(B) P(1 + r/50)n
(C) P(1 + r/100)2n
(D) P(1 – r/100)n
99. Ramen deposits Rs.100 on the first day of every month in a monthly savings scheme. In this way, he has deposited money for 1 year. If the rate of simple interest is 6% per annum; then the amount he will get at the end of the year is