Question

The compound interest on Rs 1800 at 10% per annum for a certain period of time is Rs 378. Find the time in years.

Answer 1

\[CI = P \left( 1 + \frac{R}{100} \right)^n - P\]
\[ \Rightarrow 378 = 1, 800 \left( 1 + \frac{10}{100} \right)^n - 1, 800\]
\[1, 800 \left( 1 + \frac{10}{100} \right)^n = 2, 178\]
\[ \left( 1 + \frac{10}{100} \right)^n = \frac{2, 178}{1, 800}\]
\[ \left( 1 . 1 \right)^n = 1 . 21\]
\[ \left( 1 . 1 \right)^n = \left( 1 . 1 \right)^2 \]
On comparing both the sides, we get: 
n = 2
Thus, the required time is two years .