Question

At what at what rate percent will a sum of money rupees 640 be compounded to rupees 774.40 in 2 years

Answer 1

The interest rate is 10%.

Step-by-step explanation:

The formula to compute the compounded amount is:

$A=P[1+\frac{r}{100}]^{t}$

Given:

A = Rs. 774.40

P = Rs. 640

t = 2 years

Compute the interest rate (r) as follows:

        $A=P[1+\frac{r}{100}]^{t}$

 $774.40=640[1+\frac{r}{100}]^{2}$

   $\frac{774.40}{640}=[1+\frac{r}{100}]^{2}$

$\sqrt{\frac{774.40}{640}}=[1+\frac{r}{100}]$

       $1.1=1+\frac{r}{100}$

 $1.1-1=\frac{r}{100}$

       $0.1=\frac{r}{100}$

          $r=0.1\times 100\\r=10\%$

Thus, the  interest rate is 10%.