A sum invested at a certain rate of interest per annum, compounded annually, amounts to ₹14,400 in 2 years and to ₹25,920 in 4 years. What is the sum invested?
Answer & explanation
Correct answer: option 4
Formula used here is -
Amount = P$(1 \;+\; \frac{R}{100})^t$
In 1st case,
14400 = P( 1 + \(\frac{R}{100}\))²
ATQ,
In 2nd case,
25920 = P( 1 + \(\frac{R}{100}\))4
25920 = P (\(\frac{14400}{P}\))²
On solving ,
P = 8000
So, Initial sum = Rs. 8000