A sum of ₹10000 is lent out in two parts, one at 7% simple interest and the other at 12% simple interest. If the annual interest is ₹900, the sum lent at 12% is:
Show answer & explanation
Correct answer: B
Explanation
The correct answer is option 2 i.e. ₹4000.
SI = (P × R × T)/100
Let the sum lent at 12% = x
Then the sum lent at 7% = (10000 – x)
Interest from 12% part = (x × 12 × 1)/100 = 12x/100
Interest from 7% part = [(10000 – x) × 7 × 1]/100 = [7(10000 – x)]100
Total interest = [7(10000 – x)]/100 + 12x/100 = 900
⇒ (70000 – 7x + 12x)/100 = 900
⇒ 70000 + 5x = 90000
⇒ 5x = 90000 – 70000 = 20000
⇒ x = 20000/5 = 4000