Simple Interest

A sum of money amounts to Rs. 9800 after 5 years and Rs. 12005 after 8 years at the same rate of simple interest. The rate of interest per annum is:

A certain amount earns simple interest of Rs. 1750 after 7 years. Had the interest been 2% more, how much more interest would it have earned?

What will be the ratio of simple interest earned by certain amount at the same rate of interest for 6 years and that for 9 years?

An automobile financier claims to be lending money at simple interest, but he includes the interest every six months for calculating the principal. If he is charging an interest of 10%, the effective rate of interest becomes:

A man took loan from a bank at the rate of 12% p.a. simple interest. After 3 years he had to pay Rs. 5400 interest only for the period. The principal amount borrowed by him was:

If the interest earned in 3 years is ₹450 at 6% p.a., what is the principal?

How much time will it take to earn ₹240 as simple interest on ₹1200 at 10% p.a.?

If the principal is ₹6000 and the interest earned in 4 years is ₹960, what is the rate of interest per annum?

If ₹400 earns ₹160 in 4 years, what is the rate of simple interest?

What is the formula for calculating simple interest?