Question

A certain sum of money at simple interest became rs.7,396 in two years and rs.7950.70 in three years. Find the rate of interest?

Answer 1

Answer:

Rate of interest = 7.5%

Step-by-step explanation:

☞ Given :

Amount = Rs7396

Time = 2 years

Amount for 3rd = Rs7950.70

Time = 3 years

We Know That ,

$\sf \: Amount = p \bigg(1 + \frac{r}{100} \bigg) ^{n}$

Putting the values on :

$\sf \implies 7396 = p \bigg(1 + \frac{r}{100} \bigg)^{n} \longrightarrow \: eqn \boxed{1}$

$\sf \implies \: 7950.70 = p \bigg(1 + \frac{r}{100} \bigg) ^{n} \longrightarrow \: eqn \boxed{2}$

Solving equation 1 and 2.

$\implies \sf \: \frac{7950.70}{7396} = \bigg(1 + \frac{r}{100} \bigg)$

$\sf \implies \: 1.07500 = \bigg( \frac{1 + r}{100} \bigg)$

$\sf \implies0.075 = \frac{r}{100}$

$\sf \implies \: rate \: of \: interest = 7.5\%$

What you need to know ?

• What is the formula for amount ?

$\sf \: Amount = p \bigg(1 + \frac{r}{100} \bigg) ^{n}$

Where p = principal

r = rate

n = time

• What is compound interest then ?

CI = Amount - Principal

• Well , then what is simple interest ?

SI = p×r×t / 100