Question

The difference between the C.I. and S.I. on an amount of Rs. 18,000 in 2 years was Rs. 405. What was the rate of interest % p.a. ?

• A. $10\%$
• B. $15\%$
• C. $20\%$
• D. $25\%$

Answer 1

The correct option is B $15\%$

Let the rate is R% p.a.
$\left[18000\right(1+\frac{R}{100}{)}^2-18000]-[\frac{18000\times R\times 2}{100}]=405$
$18000[(100+\frac{({R}{^2}{10000})-1-(\frac{2R}{100})]=40518000[(100+R)^2-10000-200R]=405\frac{9 R^2}{5}=405R^2=\frac{405\times 5}{9}=225R=15$
Rate of interest=15%