Lalremsiami lends ₹12,000 in two parts, one at 8% simple interest a year and the other at 12% a year. Her total interest for one year is ₹1,140. How much did she lend at 8%?

Explanation

1. 01

   Average rate = $\frac{1140}{12000} \times 100 = 9.5\%$.

2. 02

   8% part : 12% part = $(12 - 9.5) : (9.5 - 8) = 2.5 : 1.5 = 5 : 3$.

3. 03

   Amount at $8\% = \frac{5}{8} \times 12000 = 7500$ rupees.