A sum of ₹2,400 doubles in 8 years under simple interest. Another sum Q is invested at the same rate. The interest earned on Q for 5 years exceeds the interest earned on ₹2,400 for 3 years by ₹300. What is Q?
Show answer & explanation
Correct answer: A
Explanation
Given:
₹2400 doubles in 8 years
₹300 more than the interest on ₹2400 in 3 years is ₹300.
Formula:
₹SI = (P × R × T) / 100
₹2400 doubles in 8 years ⇒ Interest = 2400
₹2400 = (2400 × R × 8) / 100
₹2400 = 192R
₹R = 12.5%
Now the interest on ₹2400 in 3 years is ₹SI = (2400 × 12.5 × 3) / 100 = 900
₹5 interest on ₹900 + 300 = 1200
₹1200 = (Q × 12.5 × 5) / 100
₹1200 = 0.625Q
Q = 1920
Q = Rs 1920