A sum of money doubles itself in 8 years. What is the rate of interest?

a. A sum of money doubles itself in 4 years at a certain rate of interest. In how many years will it triple itself at the same rate of interest ? b. A sum of money trebles itself in 6 years at a certain rate of interest. In how many years will it become four times itself at the same rate of interest ?

The interest on a certain sum of money is 0*24 times of itself in 3 years. Find the rate of interest.

A sum of money, lent out at simple interest, doubles itself in 8 years. Find : (i) the rate of interest. (ii) In how many years will the sum become triple (three times) of itself at the same rate percent ?

An amount of money invested trebled in 6 years . Find the rate of interest earned .

Find the rate at which a sum of money will double itself in 3 years, if the interest is compounded annually.

A sum of 16,000, invested at simple interest, amounts to 22,400 in 4 years at a certain rate of interest. If the same sum of money is invested for 2 years at the same rate of interest, compounded p.a., find the compound interest earned.

At simple interest a sum becomes (49)/(40) of itself in 2 1/2 years. The rate of interest per annum is (a) 7% (b) 8% (c) 12% (d) 9%

A sum of money invested at a certain rate of interest doubles itself in 8 years. In how much time will it treble itself at the same interest rate ?

Simple interest on a certain sum of money at 9% is rupees 450 in 2 years . Find the compound interest. On the same sum , at the same rate for 1 year, if the interest is reckoned half yearly .

If the amounts of two consecutive years on a sum of money are in the ratio 20 : 21, find the rate of interest.