Compound Interest Maths
Posted by
Ravi Kumar at Tuesday, April 14, 2009
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Sometimes it so happens that the borrower and the lender agree to fix up a certain unit of time ,say yearly or half-yearly or quarterly to settle the previous account.
In such cases ,the amount after the first unit of time becomes the principal for the 2nd unit ,the amount after second unit becomes the principal for the 3rd unit and so
on. After a specified period ,the difference between the amount and the money borrowed is called Compound Interest for that period.
Formulae:
As we discussed in the simple interest
Let principal=p,Rate=R% per annum Time=nyears
1.When interest is compounded Annually, Amount=P[1+(R/100)]n
2.When interest is compounded Half-yearly, Amount=P[1+((R/2)100)]2n
3.When interest is compounded Quarterly, Amount=P[1+((R/4)100)]4n
4.When interest is compounded Annually,but time in fractions
say 3 2/5 yrs Amount=P[1+(R/100)]3[1+((2R/5)/100)]
5.When rates are different for different years R1%,R2%,R3%
for 1st ,2nd ,3rd yrs respectively Amount=P[1+(R1/100)][1+(R2/100)][1+(R3/100)]
6.Present Worth of Rs.X due n years hence is given by
Present Worth=X/[1+(R/100)]n