Question

At what rate of compound interest will a sum of Rs 640 amount to Rs 1250 in 3 years?

Answer 1

Answer:

apply the formula:

principal×[interest +(rate per/100) -1]

Step-by-step explanation:

hope it will help u mate

Answer 2

Answer:

The rate of compound interest is 25%.

Step-by-step explanation:

Given the principal amount, P = Rs 640

Final amount, A = Rs 1250

Number of years, n = 3

And let the rate of interest per annum be R%.

Compound interest is the interest accrues on principal plus interest.

The formula for compound interest is

$A=P\Big(1+\frac{R}{100} \Big)^{n}$

Substituting the values,

$1250=640\Big(1+\frac{R}{100} \Big)^{3}$

$\frac{1250}{640} =\Big(1+\frac{R}{100} \Big)^{3}$

$\big(1+\frac{R}{100} \big)^{3} =\big(\frac{5}{4}\big)^{3}$

$\implies 1+\frac{R}{100} =\frac{5}{4}$

$\implies \frac{R}{100} =\frac{5}{4}-1$

$\implies R =\frac{1}{4}\times 100=25$

Hence, the rate of compound interest is 25%.