Raju lent Rs. 400 to Ajay for 2 years and Rs. 100 to Manoj for 4 years and received together from both Rs. 60 as interest. Find the rate of interest, simple interest being calculated.

A. 5% B. 6% C. 8% D. 9% Answer: Option A
$\begin{array}{l}\text{Let rate is R%}\\ \text{According to the question,}\\ \begin{array}{l} {\left[\frac{400 \times 2 \times R}{100}\right]+\left[\frac{100 \times 4 \times R}{100}\right]=60} \\ 8 R+4 R=60 \\ \text { Hence, } R=5 \% \end{array}\end{array}$