Find the rate of simple interest per annum. If the sum borrowed becomes 3 times itself in 12 years.

Find the rate of simple interest per annum, if a sum borrowed becomes double in 5 years.

A sum becomes 14 times of itself in 15 years at the rate of simple interest per annum. In how many years will the sum becomes 92 times of itself?

If a sum of money at a certain rate of simple interest per year doubles in 5 years and at a different rate of simple interest per year becomes three times in 12 years, then the difference in the two rates of simple interest per year is

At the same rate of simple interest in percent per annum, if a principal becomes the amount of Rs 1248 in 7 years and or Rs 1056 in 4 years. Find the principal and rate of simple interest in percent per annum.

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