A sum of money doubles itself at compound interest in 15 years. In how many years it  will become eight times?

If the difference between 2 years compound interest and simple interest at the rate of 5 percent of an amount is Rs. 25, then that amount will be?

If the compound interest on a certain sum for 2 years at 4% p.a. is Rs. 102, the simple interest at the same rate of interest for two years would be:

The compound interest on a certain sum of money for 2 years at 5% per annum is Rs. 410. The simple interest on the same sum at the same rate and for the same time is-

A sum of Rs. 8000 will amount to Rs. 8820 in 2 years if the interest is calculated every year. The rate of compound interest is 

A person borrows Rs.1,00,000 from a bank at 10% per annum simple interest and clears the debt in five years. If the instalment paid at the end of the first, second, third and fourth years to clear the debt are Rs.10,000, Rs.20,000, Rs.30,000 and Rs.40,000, respectively, what amount should be paid at the end of the fifth year to clear the debt?

What will be the difference between the compound interest and simple interest of 2 years at the rate of 5 percent annual interest at Rs. 4,000?

If the difference between the compound and simple interest on a certain sum of money for 3 years at 5 % per annum is Rs. 15.25, then the sum is