Question Discussion

Discussion

Q.	The difference between compound interest and simple interest on a certain sum in 3 years at 10% p.a. is ₹ 155. Find the sum.

General Method

$P {(1 + \frac{10}{100})}^{3} - P - \frac{P \times 10 \times 3}{100} = 155$

After solving for P, we will get P = ₹ 5000

AB Method

SI = 10×3 = 30% ( In 1 year SI = 10%, In 3 years SI = 30%

CI = 33.1% (Applying AB method twice. $10 + 10 + \frac{10 \times 10}{100} = 21$ , $21 + 10 + \frac{21 \times 10}{100} = 33.1 %$ )