AFCAT Model Paper 3

Given: Amount = 9 × Principal, Time 32 years Formula Used: Let P = principal, N = time and R = rate percent per annum Then, Simple interest $= \frac{P \times N \times R}{100}$ Calculation: According to the question Amount = S.I + Principle $9P = \left(\frac{P \times 32 \times R}{100}\right) + P$ ⇒ 900P = 32PR + 100P ⇒ 800 = 32R ⇒ R $= \frac{800}{32}$ ⇒ R = 25% Now, Again according to the question $19P = \left(\frac{P \times N \times 25}{100}\right) + P$ $\Rightarrow 19P = \frac{NP}{4} + P$ $\Rightarrow 19 = \frac{N}{4} + 1$ ⇒ 76 = N + 4 ⇒ N = 76 - 4 ⇒ N = 72 ∴ In 72 years, amount will becomes 19 times its principle.