At what rate percent compound interest per annum will Rs. 640 amounts to Rs. 774.40 in 2 years?

A lady shopkeeper allows her customers 10% discount on the marked price of the goods and still gets a profit of 25%. What is the cost price of a fan for her marked at Rs. 1250.

A sum of money was lent for 2 years at 20% compounded annually. If the interest is payable half-yearly instead of yearly, then the interest is Rs. 482 more. Find the sum.

Rs 3500 is to be shared among three people so that the first person gets 50%of the second, who in turn gets 50% of the third. How much will each of them get?

Arun bought a pair of skates at a sale where the discount given was 20%. If the amount he pays is Rs 1,600, find the marked price.