Compound Interest - General Questions

Find the compound interest on Rs. 16,000 at 4% per annum for 1 year, compounded half-yearly.

A sum amounts to Rs. 2,300 in 2 years and to Rs. 2,875 in 3 years at compound interest. What is the rate of interest?

A sum amounts to Rs. 7,400 in 2 years and to Rs. 8,880 in 3 years at compound interest. What is the rate of interest?

A sum amounts to Rs. 5,100 in 2 years and to Rs. 5,355 in 3 years at compound interest. What is the rate of interest?

What is the compound interest on Rs. 1,900 at 20% per annum for 2 years, compounded annually?