Quantitative Aptitude :: Compound Interest

1. When interest is compound Annually:

Amount = \(P \left(1 \ + \ \frac{R}{100}\right)^{n}\)

2. When interest is compounded Half-yearly:

Amount = \(P \left[1 \ + \ \frac{\frac{R}{2}}{100}\right]^{2n}\)

3. When interest is compounded Quarterly:

Amount = \(P \left[1 \ + \ \frac{\frac{R}{4}}{100}\right]^{4n}\)

4. When interest is compounded Annually but time is in fraction, say \(2\frac{1}{5}\) years.

Amount = \(P \left(1 \ + \ \frac{R}{100}\right)^{2} \ \times \ P \left[1 \ + \ \frac{\frac{1}{5} \times R}{100}\right]\)

5. When Rates are different for different years, say R1%, R2%, R3% for 1st, 2nd and 3rd year respectively.

Then, Amount = \(P \left(1 \ + \ \frac{R1}{100}\right) \left(1 \ + \ \frac{R2}{100}\right) \left(1 \ + \ \frac{R3}{100}\right)\) .

6. Present worth of Rs. x due n years hence is given by:

Present Worth = \(\left[\frac{x}{\left(1 \ + \ \frac{R}{100}\right)}\right]\)