Naina lent Rs. 10,000 to Mohini for 4 years and Rs. 15,000 to Mitali for 6 years on simple interest at the same rate of interest and received Rs. 2,600 in all from both as interest. The rate of interest per annum is.
Let the rate of interest r % per annum According to the question, (10000 × 4 × r)/100 + (15000 × 6 × r)/100 = 2,600 ⇒ 400r + 900r = 2,600 ⇒ 1300 r = 2,600 ⇒ r = 2%