Simple Interest :

1. Find the simple interest on 10400 for 2 years at 6% per annum.

Solution : Here, P= Rs. 10400, T = 2 years and R = 6%

∴ Simple interest = P×R×T/100 = 10400×6×2/100

= Rs. 1248

2. A Woman earns Rs. 900 as an interest in 2 years on a certain sum invested with a company at the rate of 12 % per annum. Find the sum invested by the Woman in the company.

Solution : We have, I = Rs. 900, T= 2 years, R= 12% per annum

∴ P= I×100/R×T=900×100/12×2

= Rs. 3750

3. At what rate per annum will a sum of Rs. 10000 amount to Rs. 12000 in 4 years ?

Solution : Here, P = Rs.10000, A = Rs12000, T= 4 years

So, I = A − P = Rs. (12000 – 10000) = Rs. 1000

∴ R = 100×I/P×T = 100×2000/10000×4 =5%

4. In what time will Rs. 2400 earn an interest of Rs. 480 at 5% per annum ?

Solution : Here, P = Rs.2400, I = Rs.480, R= 5%

∴ T = 100×I/P×R = 100 × 480/2400 × 5

= 4 years.

5. Dipen borrowed Rs. 6000 from his friend Rathin at 15% per annum for 3 years. Find the interest and money returned by Dipen to Rathin.

Solution : Here, P = Rs.6000, R = 15% per annum, T= 3 years

∴ I = P×R×T/100 = 6000 × 15×3/100 = Rs. 2700

∴ A = P + I = Rs. 6000 + Rs. 2700 = Rs. 8700

Thus, Dipen paid Rs. 2700 as interest to Rathin and the amount returned by Dipen to Rathin = Rs. 8700