SIMPLEINTREST QUESTIONS AND ANSWERS
1) A principle amount Rs12,500 becomes Rs 15,500 in 3years at the rate of ------- simple interest?
Ans:Total interest = Rs. (15500 - 12500) = Rs. 3000. Interest Rate = [ (100 × 3000) / (12500 × 3) ] % = 8 %.
2) A sum fetched a total simple interest of Rs. 116.25 at the rate of 11 p.c.p.a. in 5 years. What is the sum?
Ans:- Principal = Rs. [(100 × 116.25) / (11 × 5) ] = Rs. ( 11625 / 55 ) = Rs. 211 .
3) A sum of money lent out at simple interest amount to Rs. 820 after 2 years and to Rs. 1200 after a further period of 5 years. The sum is?
Ans:• Simple interest for 5 years = Rs. (1200 -820) = Rs. 380. • Simple interest for 2 years = Rs. ( 380/5 × 2) = Rs. 152. • ∴ Principal = Rs. (820 - 120) = Rs. 700.
4) A sum of money at simple interest amounts to Rs. 8150 in 3 years and to Rs. 8540 in 4 years. The sum is?
Ans:- • Simple interest for 1 year = Rs. (8540 - 8150) = Rs. 390. • Simple interest for 3 year = Rs. (390 × 3) = Rs. 1170. • So, Principal amount = Rs. (8150 - 1170) = Rs. 6980.
5) A sum of Rs. 2800 gives a simple interest of Rs. 462 in 2 years and 4 months. The rate of interest per annum is?
Ans:Time = 2 years 4 months = 2 1/3 years = 7/3 years. Rate = [ (100 × 462 × 3)/(2800 × 7) ] % = 7 % .
6) Calculate the simple interest earned on an amount of Rs. 2,00,800 in 9 months at the rate of 7 1/4 % p.a. ? Ans:-
• Here 9 months = 3/4 year. • ∴ S.I. = Rs. [ 200800 × 29/4 × 3/4 × 1/100 ] = Rs. 10918.5.
7) Calculate the simple interest on Rs. 27,500 from March 9, 2003 to May 21, 2003 at 8 1/2 % rate will be?
Ans:Time = (22 + 30 + 21) = 73 days = 1/5 year. Simple interest = Rs. [ 27500 × 17/2 × 1/5 × 1/100 ] = Rs. 467.50.
8) Find the time needed to get 81rs as interest, where 450rs is capital and 4.5% is the rate of interest? Ans:- Time needed = [ (100 × 81) / (450 × 4.5) ] years = 4 years.
9) If the annual rate of simple interest increases from 10% to 12 1/2 % , Rohan’s yearly income increases by Rs. 1250. Find his principal amount (in Rs.) ?
Ans:- Let the sum = Rs. S. Then, S × 25/2 × 1/100 - (S × 10 × 1)/100 = 1250 ↔ 25S - 20S = 250000 ↔ 5S = 250000 ↔ S = 50000.
10) In how many years will a sum of principal amount double itself at 15% per annum?
Ans:Let sum = C. Then, S.I = C. ∴ Time = [ (100 × S.I.) / (P × R) ] = [ (100 × C) / (C × 15) ] = 6 2/3 years.