Question

4. The compound interest, calculated yearly, on
a certain sum of money for the second year
is 1,089 and for the third year it is?
1,197.90. Calculate the rate of interest and the
sum of money.​

Answer 1

Answer:

rate of interest = 10%

sum of money = ₹900

Step-by-step explanation:

Sum after 2 years=Rs.1089

Sum after 3 years=Rs.1197.90

Interest for one year=1197.90 − 1089 = 108.90

C.I for 1 year = S.I for 1 year

$Interest = \frac{PRT}{100}$

=> $108.90 = \frac{1089 * R *T}{100}$

=> $R = \frac{108.90 * 100}{1089}$  = 10%

________________________________________

let the sum = x

Amount= ₹ 1089,Time 2 years, R=10%

$Amount=P(1 + \frac{R}{100} )^t$

$1089=x(1 + \frac{10}{100} )^2$

$1089=(x)(\frac{110}{100})( \frac{110}{100})$

$x = \frac{(1089)(100)(100)}{(110)(110)}$

$x = 900$