Calculate the amount and compound interest on

(a) Rs 10800 for 3 years at per annum compounded annually.

(b) Rs 18000 for years at 10% per annum compounded annually.

(c) Rs 62500 for years at 8% per annum compounded half yearly.

(d) Rs 8000 for 1 year at 9% per annum compound half yearly.

(You could use the year by year calculation using SI formula to verify)

(e) Rs 10000 for 1 year at 8% per annum compounded half yearly.

(a) Principal (P) = Rs 10, 800

Rate (R) = = % (annual)

Number of years (n) = 3

Amount, A =

C.I. = A − P = Rs (15377.34 − 10800) = Rs 4,577.34

(b) Principal (P) = Rs 18,000

Rate (R) = 10% annual

Number of years (n) =

The amount for 2 years and 6 months can be calculated by first calculating the amount for 2 years using the compound interest formula, and then calculating the simple interest for 6 months on the amount obtained at the end of 2 years.

Firstly, the amount for 2 years has to be calculated.

By taking Rs 21780 as principal, the S.I. for the next year will be calculated.

∴ Interest for the first 2 years = Rs (21780 − 18000) = Rs 3780

And interest for the nextyear = Rs 1089

∴ Total C.I. = Rs 3780 + Rs 1089 = Rs 4,869

A = P + C.I. = Rs 18000 + Rs 4869 = Rs 22,869

(c) Principal (P) = Rs 62,500

Rate = 8% per annum or 4% per half year

Number of years =

There will be 3 half years inyears.

C.I. = A − P = Rs 70304 − Rs 62500 = Rs 7,804

(d) Principal (P) = Rs 8000

Rate of interest = 9% per annum or % per half year

Number of years = 1 year

There will be 2 half years in 1 year.

C.I. = A − P = Rs 8736.20 − Rs 8000 = Rs 736.20

(e) Principal (P) = Rs 10,000

Rate = 8% per annum or 4% per half year

Number of years = 1 year

There are 2 half years in 1 year.

C.I. = A − P = Rs 10816 − Rs 10000 = Rs 816