Simple Interest - Aptitude Questions and Answers - RejinpaulPlacement

22.
What is the present worth of Rs. 132 due in 2 years at 5% simple interest per annum ? [C.B.I 1997]

Solution:   Let the present worth be Rs. x.
Then, S.I. = Rs. (132 - x)

(x * 5 * 2)/100 = 132 - x
=> 10x = 13200 - 100x
=> 110x = 13200
=> x = 120
23.
A sum fetched a total simple interest of Rs. 4016.25 at the rate of 9 p.c.p.a. in 5 years. What is the sum? [NABARD. 2002]

Solution:   Principal = Rs. [(100 * 4016.25)/(9 * 5)]
= Rs. (401625/45)
= Rs. 8925.
24.
The simple interest at x % for x years will be Rs. x on a sum of:

Solution:   Sum = (100 * S.I)/(R * T)
= Rs. (100 * x)/(x * x)
= Rs. (100/x)
25.
Rs. 800 becomes Rs. 956 in 3 years at a certain rate of simple interest. If the rate of interest is increased by 4 %, what amount will Rs. 800 become in 3 years? [Bank P.O 2000]

Solution:   S.I. = Rs. (956 - 800) = Rs. 156.

Rate = (100 * 156)/(800 * 3) = % = 6 1/2 %

New rate = [6 1/2 + 4]% = 10 1/2 %.

New S.I. = Rs. [800 * (21/2) * (3/100)] = Rs. 252.

New amount = Rs. (800 + 252) = Rs. 1052.
26.
A certain amount earns simple interest of Rs. 1750 after 7 years. Had the interest been 2 % more, how much more interest would it have earned? [Bank P.O. 2003]

Solution:   We need to know the S.I., principal and time to find the rate. Since the principal is not given, so data is inadequate.
27.
In how many years, Rs. 150 will produce the same interest @ 8 % as Rs. 800 produce in 3 years @ 4   1/2 %? [R.B.B. 2001]

Solution:   P = Rs. 800, R = 4   1/2 %, T = 3 years. Then,

S.I. = Rs. [800 * (9/2) * (3/100)] = Rs. 108.

Now, P = Rs. 150, S.I. = Rs. 108, R = 8%

Time = (100 * 108)/(150 * 8) years = 9 years
28.
The simple interest on a certain sum of money at the rate of 5% p.a. for 8 years is Rs. 840. At what rate of interest the same amount of interest can be received on the same sum after 5 years?