Question

At whatcrate of interest compound interest/per annum will rs 640 amount to rs.774.40 in 2 years

Answer 1

Step-by-step explanation:

Given: Amount = Rs.774.40

Principal = Rs.640

Time = 2 years

We know that

$amount \: = p {(1 + \frac{r}{100}) }^{t}$

$= > 774.40 = 640 {(1 + \frac{r}{100}) }^{2}$

$= > \frac{774.40}{640} = {(1 + \frac{r}{100}) }^{2}$

$= > \frac{77440}{64000} = {(1 + \frac{r}{100}) }^{2}$

$= > \frac{7744}{6400} = {(1 + \frac{r}{100}) }^{2}$

$= > {( \frac{88}{80}) }^{2} = {(1 + \frac{r}{100} )}^{2}$

$= > \frac{88}{80} = 1 + \frac{r}{100}$

$= > \frac{88}{80} - 1 = \frac{r}{100}$

$= > \frac{8}{80} = \frac{r}{100}$

$= > r = \frac{8 \times 100}{80}$

$= > r = 10$

Required run rate = 10%