A sum of ₹9000 amounts to ₹13356 at a certain rate percent per annum in $4\frac{2}{5}$years at simple interest. What will be the simple interest on the same sum at double the rate for $2\frac{1}{3}$years.

₹4620

Simple Interest = 13356 - 9000 = 4356

Simple Interest = $\frac{Principal ×Rate × Time }{100}$

4356 = $\frac{9000 ×Rate × 22 }{5×100}$

Rate = 11%

Now ,

Double of rate = 2 × 11% = 22%

Simple interest = $\frac{9000 × 7 × 22}{3×100}$

= Rs. 4620