Rs. 1,080 invested for 3 months gave an interest of Rs. 27. The simple rate of interest per annum was :

A certain sum of money lent out at simple interest amounts to Rs. 2400 in 4 years and Rs. 3000 in 6 years. Find the rate of interest per annum?

A sum of money was invested at a certain rate of simple interest for 2 years. Had it been invested at 1% higher rate, it would have fetched Rs.192 more interest. The sum of money is-

The simple interest and the true discount on a certain sum for a given period and at a given rate are 25 and 20 respectively. The sum is 

2 years, a sum was put at SI at a certain rate. If the rate was 3 % higher, it would have fetched 300 more. What will be the sum? 

A sum of money becomes two times of itself in 8 years at simple interest, and it becomes four times of itself in 2 years at compound interest, when interest is compounded annually. Find the ratio of the rate of simple interest to the rate of compound interest offered per year.

The amount of Rs 400 becomes Rs 480 in 4 years. If the rate of interest is increased by 2 percent, how much will it be?

If an amount doubles automatically in 8 years, then what is the interest rate?