Question

An amount of rs. 45000 becomes rs. 77400 on simple interest in 8 yr. What of the rate of interest percent per annum?

Answer 1

The rate of interest percent per annum is 7%.

Step-by-step explanation:

Given : An amount of rs. 45000 becomes rs. 77400 on simple interest in 8 yr.

To find : What of the rate of interest percent per annum?

Solution :

Using compound interest formula,

$A=P(1+r)^t$

Where,

A is the amount A=Rs.77400

P is the principal P=Rs.45000

r is the interest rate

t is the time t=8 years.

Substitute the value in the formula,

$A=P(1+r)^t$

$77400=45000(1+r)^8$

$\frac{77400}{45000}=(1+r)^8$

$1.72=(1+r)^8$

Taking eight root both side,

$\sqrt[8]{1.72}=1+r$

$1.070=1+r$

$r=0.070$

In percentage, $r=0.070\times 100=7\%$

Therefore, the rate of interest percent per annum is 7%.

#Learn more

At the same rate of simple interest in percent per annum, if a principal becomes the amount of Rs. 7100 in 7 yrs. and of Rs. 6200 in 4 yrs. Let us determine the principal and rate of simple interest in percent per annum.

(Answer : P = Rs. 5000, R = 6%)

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Answer 2

Answer:

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