Question

what rate of simple interest per annum if a sum borrowed becomes double in 5 years ?

Answer 1

Solution :

Let the principal ( p ) = Rs x

Amount ( A ) = Rs 2x

Simple interest ( I ) = A - P

= 2x - x = Rs x


Time ( t ) = 5 years

Let the rate of interest = r%

We know that ,

( ptr )/100 = I

=> r = ( 100 × I )/( pr )

=> r = ( 100 × x )/( x × 5 )

=> r = 100/5

=> r = 20%

Therefore ,

Rate of interest ( r ) = 20%

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