A lent Rs. 5000 to B for 2 years and Rs. 3000 to C for 4 years on simple interest at the same rate of interest and received Rs. 2200 in all from both of them as interest. The rate of interest per annum is:
5%
7%
7$ \dfrac{1}{8} $%
10%
Explanation:
Let the rate be R% p.a.
Then,$ \left(\dfrac{5000 \times R \times 2}{100} \right) $+$ \left(\dfrac{3000 \times R \times 4}{100} \right) $= 2200.
$\Rightarrow$ 100R + 120R = 2200
$\Rightarrow$ R =$ \left(\dfrac{2200}{220} \right) $= 10.
$\therefore$ Rate = 10%.