Two pipes P and Q can fill a cistern in 36 and 48 minutes respectively. Both pipes are opened together, after how many minutes should Q be turned off,so that the cistern be fill in 24 minutes?

A vessel contain some litres of pure milk. If 25 litre of water is added to the vessel, then ratio between milk and water becomes 12:5, 17 litres of mixture is drawn from the vessel and 10 litre of water is added to the mixture. Find the new ratio between milk and water. 

The price of the book is marked 20% above the C.P. If the market price of the book is Rs. 180, then what is the cost of the paper used in a single copy of the books?

By selling a table for Rs. 350 instead of Rs. 400, loss percent increases by 5%. The cost price of table is : 

In how many ways can a committee schedule three speakers for three different meetings if they are all available on any of five possible dates?

In a village, 70 % registered voters cast their votes in the election. Only two candidates (A and B) contested the election. A won the election by 400 votes. Had A received 12.5 % less votes, the result would have been tie. How many registered voters are there in the village?