A certain sum amounts to Rs. 13860 after 5 years and to Rs. 16776 after 8 years at the same rate per cent per annum at simple interest. What will be simple interest (in Rs.) on a sum of Rs. 20,000 for \(3 \frac{2}{5}\) years at the same rate?
1
7344
2
7434
3
6374
4
6473