Puzzle | The Water MasterChef

A specific water tank requires precisely 7L of water. The problem arises as you do not have glass to measure exactly 7L. You have two glasses of 4L and 5L. How can it be accomplished?

Two glasses of 4L and 5L, need to fill up the tank of 7L.

Solution: The above precision can be achieved easily.

First, pour water into the 5L glass and, using the 5L glass fill the 4L glass. This way, 5L glass will be left with 1L of water. 
Pour this 1L into the dish. Repeat the process. 

Emptying 5L Bucket to 4L, thus 5L now contains only 1L. 

Now you have added 2L of water. Finally, add 5L of water using a 5L glass.