Question

If ₹ 8000 amounts to ₹ 9261 in 3 years at compound interest, find the rate of interest per annum.​

Answer 1

Answer:

5%

Step-by-step explanation:

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Answer 2

Given:

If ₹ 8000 amounts to ₹ 9261 in 3 years at compound interest,

To Find:

Find the rate of interest per annum.​

Solution:

We are given that Rs8000 amounts to Rs9261 in 3 years at compound interest and we need to find the rate of interest per annum, first, we should know the formula for the amount of compound interest at the end of the time period,

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

Where,

           A= Final amount

           P= Principal amount

           r= rate of interest

           t= time period

Now put the values of the same according to the question and find the value of the rate of interest,

$9261=8000(1+r)^3\\1+r=\sqrt[3]{\frac{9261}{8000} } \\1+r=\frac{21}{20} \\1+r=1.05\\r=0.05\\r=5\%$

We took the cube root to find the value by keeping the value under root as pair of 3 numbers that were for 9261=21*21*21 and for 8000=20*20*20

Hence, the rate of interest is 5%.