A certain sum is invested at simple interest at 18% p.a. for two years instead of investing at 12% p.a. for the same time period. Therefore the interest received is more by Rs. 840. Find the sum  ?

What is the ratio of simple interest earned on certain amount at the rate of 12% p.a. for 9 years and that for 12 years?

The difference between simple interest on a certain sum at the rate of 6% per annum for 5 years and 6 years is 25.8. What is the sum (in Rs)?

What is the ratio of simple interest earned on certain amount at the rate of 12% for 6 years and that for 12 years?

R borrowed Rs. 1,200 at 13% per annum simple interest. What amount will R pay to clear the debt after 5 years?

A sum of Rs 4000 becomes Rs 7000 in 6 years at simple interest. If the rate of interest becomes double of itself, then what will be the amount (in Rs) after 6 years?

A sum of Rs 800 becomes Rs 1000 in 2 years at simple interest. What is the per annum rate of interest (in percent)?

Sachin lent out Rs 60000 in two parts, first at 4% and the second at 10% interest. The yearly average interest comes out to be 6.4%. What are the amounts (in Rs) that were lent at 4% and 10% respectively?

Rs. x invested at 8% simple interest per annum for 5 years yields the same interest as that on Rs. y invested at 7.5% simple interest per annum for 6years. Find x : y.