In how many years, a certain sum becomes tripe itself at `12%` p.a.?

In how many years will a certain sum become 3 times itself at 25% per annum under simple interest? (a) 5 (b) 8 (c) 12 (d) 6

In how many years will a certain sum becomes five times itself at 20% per annum simple interest?

In how many years will a certain sum become 3 xx itself at 25% per annum under simple interest? 5 (b) 812 (d) 6

In how many years will a certain sum amounts to 6 times itself at 25% per annum simple interest ?

If certain sum becomes 3 times itself in 4 years at compound interest, in how many years will the sum become 81 times itself at the same rate of interest?

In how many years will a sum of money become sixteen times itself at 30% p.a. simple interest?