Compound Interest - General Questions

Find the amount on Rs. 4,000 for 3 years at 10% per annum compounded annually.

Find the amount on Rs. 2,000 for 3 years at 10% per annum compounded annually.

A sum amounts to Rs. 7,000 in 2 years and to Rs. 8,750 in 3 years at compound interest. What is the rate of interest?

What is the compound interest on Rs. 16,000 at 15% per annum for 2 years, compounded annually?

A sum of money doubles itself at compound interest in 2 years. In how many years will it become four times?