Question

A certain amount of money deposited at compound interest becomes 3 times itself in 3 years. In how many years would that amount be 81 times the deposited amount if it is invested at the same rate of interest?

Answer 1

A certain sum of money doubles itself in 8 years. In how much time will it become 4 times of itself at the same rate of interest?

Let the principle be 100.

Then amount will be 200.

Interest= 100

Time = 8 yrs

R=?

I=PRT/100

100=100*R*8/100

100*100/100*8=R

100/8=R

NOW SUM SHOULD BE 4 TIMES MEANS 400

MEANS INTREST ON 100 IS 300.

I=PRT/100

300=100*100/8*T/100

300*8/100=T

24= T

IN 24 YEARS SUM WILL BECOME 4 TIMES OF PRINCIPLE.