A certain sum doubles itself in 4 years. Find the time taken to it to become thrice itself.

A sum of money doubles itself in 7 years. In how many years it will become 4 times ?

A sum of money invested at compound interest doubles itself in six years. In how many years will it become 64 times itself at the same rate of compound interest?

A certain amount of sum is invested at simple interest. If the sum becomes k times itself in 16 years and 2k times itself in 40 years, in how many year will it become 4k times of itself?

A sum of money placed at compound interest doubles itself in 4 years. In how many years will it amount to eight times itself ?

A sum of money placed at com pound interest doubles itself in 4 years. In how many years will it amount to four times itself ?

A certain sum of money becomes (5)/(4) times of itself in 4 years. Find the Rate of interest.

A certain sum of money becomes 3 times of itself in 50years. Find the Rate of interest.