A certain sum was invested at a certain rate at simple interest. It took 8 years to quadruple the sum. Find the time it would take to become 10 times itself (in years).

A certain sum was invested at a certain rate of simple interest. It took 20 years to quadruple. Find the time that the sum would take to become 9 times, if the rate of interest was 5 percentage points more (in years).

A certain sum becomes 3 times itself in 6 years at simple interest. In how many years will it become 9 times itself ?

A certain sum becomes doubled in 5 years. Find the rate of interest.

A certain sum doubles in 3 years under simple interest. In how many years will the sum become 5 times itself?

A sum of money invested at simple interest triples itself in 8 years at simple interest. Find in how many years will it become 8 times itself at the same rate?

A certain sum in invested on simple interest If it triples in 10 years, what is the rate of interest ?