What is the quantity of water should be added to a 75 litre mixture of milk and water so that the percentage of milk in the mixture decrease from 75% to 45%?

If the cost of production of an article is 2/5 of its marked retail price, If it is sold at 10 % discount then what will be profit ? 

A boat goes 12 km downstream and comes back to the starting point in 3 hours. If the speed of the current is 3 km/hr, then the speed (in km/hr) of the boat in still water is : 

Suresh, Dinesh and Ramesh became partners in a business by investing money in the ratio of 3 : 6 : 8. If their investments is increased by 5%, 15% and 20%, respectively, then what will be the ratio of their profits for one year? 

A train moves past a telegraph post and a bridge 264 m long in 8 seconds and 20 seconds respectively. What is the speed of the train? 

A trader had 16 quintals of wheat. He sold a part of it at 17% profit and the rest at 27% profit, so that he made a total profit of 21%. How much wheat did he sell at 27 % profit? 

A particular job can be completed by a team of 10 men in 12 days, The same job can be completed by a team of 10 women in 6 days. How many days are needed to complete the job if the two teams work together?

The length, width and height of a rectangular tank are 7 meters, 6 meters and 5 meters respectively, what will be the volume (cubic metre)  of this tank?