If 5500 copies are published and the transportation cost on them amounts to Rs. 82,500, then what should be the selling price of the book so that the publisher can earn a profit of 25%?

A tap drips at a rate of one drop/sec. 600 drops make 100ml. The number of litres wasted in 300 days is: 

Inside a square ABCD, triangle BEC is an equilateral triangle. If CE and BD intersect at O, then ∠BOC is equal to?

5 number whose average is 76, the first is 3/7 times the sum of other 4. the first number is: 

12 pumps working 6 hours a day can empty a completely filled reservoir in 15 days. How many such pumps working 9 hours a day will empty the same reservoir in 12 days?

What will come in place of question mark (?) in the following series?
8, 10, 18, 44, 124, ?

A money - lender, lends a part of his money at 10 % per annum and the rest at 15 % per annum. His annual income is 1,900. However, if he had interchanged rate of interest on the two sums, he would have earn 200 more. The amount lent will fatch what amount at 15 % ?