Simple Interest - General Questions

What is the simple interest on Rs. 12,000 at 12% per annum for 6 years?

A sum of Rs. 7,000 becomes 4 times itself in 5 years at simple interest. What is the rate of interest?

A sum of Rs. 12,000 becomes 2 times itself in 8 years at simple interest. What is the rate of interest?

At 10% per annum simple interest, what principal yields Rs. 2,500 as interest in 5 years?

A sum of Rs. 3,000 becomes 3 times itself in 8 years at simple interest. What is the rate of interest?