Mohit invests ₹ 8000 for 3 years at a certain rate of interest, compounded annually. At the end of one year, it amounts to ₹ 9440. Calculate :

(i) the rate of interest per annum.

(ii) the amount at the end of the second year.

(iii) the interest accrued in the third year.

(i) Given,

Mohit invests ₹ 8000 (P)

Amount at end of one year = ₹ 9440

Interest = Amount - P = ₹ 9440 - ₹ 8000 = ₹ 1440.

∴ ₹ 1440 is the interest of one year on ₹ 8000.

By formula,

Rate of interest = $\dfrac{I \times 100}{P \times T} = \dfrac{1440 \times 100}{8000 \times 1} = \dfrac{144}{8}$ = 18%.

Hence, rate of interest = 18%.

(ii) For second year :

P = ₹ 9440

R = 18%

T = 1 year

I = $\dfrac{P \times R \times T}{100} = \dfrac{9440 \times 18 \times 1}{100} = \dfrac{169920}{100}$ = ₹ 1699.20

Amount = P + I = ₹ 9440 + ₹ 1699.20 = ₹ 11,139.20

Hence, amount at the end of second year = ₹ 11,139.20

(iii) For third year :

P = ₹ 11,139.20

R = 18%

T = 1 year

I = $\dfrac{P \times R \times T}{100} = \dfrac{11139.20 \times 18 \times 1}{100} = \dfrac{200505.60}{100}$ = ₹ 2,005.06

Hence, interest accrued in third year = ₹ 2,005.06