Interesting Quiz on ‘INTEREST’ Calculations!



Where, P=Principal Amount

T=Time period in years

R= Rate of interest in percentage

  • If rate of interest differs year to year then
    SI = Principal * TimePeriod*(R1+R2+R3……..)/100
  • If a sum of money  is divided into n parts with r1% interest for t1 years, r2% interest for t2 years, r3% interest for t3 years then the ratio of the sum divided into n parts is:
     ( 1/r1*t1) : (1/r2*t2) : (1/r3*t3)


  • If the sum  becomes n times in t years at Simple interest,then formula for calculating interest is…
  • If a sum becomes n times at certain rate of interest in t years.Then the time taken to make the same amount N times with same interest rate is =(N-1)/2*t


The difference between the amount and money borrowed is compound interest.



Where,  CI= Compound Interest

P=Principal amount,

r=Rate of interest,

n=Number of years,


  • When compound interest is calculated half yearly then r=r/2% and n=2n A=p[1+(r/2*100)2n]
  • When compound interest is calculated Quarterly then r=r/4% and n=4n A=p[1+(r/4*100)4n]
  • The difference between compound interest and simple interest over 2 years  is given by p(r/100)2
  • The difference between compound interest and simple interest over 3 years  is given by  p(r/100)3 * {(r/100)+3}

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?

Reena took a loan of Rs. 1200 with simple interest for as many years as the rate of interest. If she paid Rs. 432 as interest at the end of the loan period, what was the rate of interest?

A sum of Rs. 12,500 amounts to Rs. 15,500 in 4 years at the rate of simple interest. What is the rate of interest?

A bank offers 5% compound interest calculated on half-yearly basis. A customer deposits Rs. 1600 each on 1st January and 1st July of a year. At the end of the year, the amount he would have gained by way of interest is:

The difference between simple and compound interests compounded annually on a certain sum of money for 2 years at 4% per annum is Re. 1. The sum (in Rs.) is:


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