There is 60% increase in an amount in 6 years at simple interest. What will be the compound interest of Rs. 12,000 after 3 years at the same rate?

Rs. 2160

Rs. 3120

Rs. 3972

Rs. 6240

Explanation:

Let P = Rs. 100. Then, S.I. Rs. 60 and T = 6 years.

$\therefore$ R =$ \left(\dfrac{100 \times 60}{100 \times 6} \right) $= 10% p.a.

Now, P = Rs. 12000. T = 3 years and R = 10% p.a.

$\therefore$ C.I.	= Rs.$ \left[12000 \times\left\{\left(1 +\dfrac{10}{100} \right)^3- 1\right\}\right] $
	= Rs.$ \left(12000 \times\dfrac{331}{1000} \right) $
	= 3972.