Question

A sum of money becomes 2200 after three years and 4400 after six years on compound interest is

Answer 1

Let the sum be P and rate of interest be R% per annum.

Amount after 3 years = 2200

P(1 + R/100)T = 2200

P(1 + R/100)3 = 2200        --- ( 1)

Amount after 6 years = 4400

P(1+R/100)T = 4400

P(1 + R/100)6 = 4400    --- (2)

(2) ÷ (1) => [P(1+R/100)6]/[P(1+R/100)3] = 4400/2200 = 2

=> (1+R/100)3 = 2  (Substituting this value in equation 1)

=> P × 2 = 2200

P = 22002 = 1100