Question

If a sum of money at simple interest, doubles in 12 years, the rate of interest per annum is?
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Answer 1

Given :-

Sum of a money at simple interest , doubles in 12 years.

To Find :-

The rate of interest per annum.

Answer :-

Rate per annum = 25/3 %

Solution :-

Let , principal = p

Given , time ( t ) = 12 years

And , interest ( I ) = ( 2p - p ) = p

And let , rate per annum is r%

•°• Now , as per identity ,

I = ptr / 100

=> p = p × 12 × r / 100

=> 12r = 100

=> r = 100 / 12

=> r = 50 / 6

=> r = 25 / 3

•°• Rate per annum ( r% ) = 25/3 % [ • Required Answer ]