Question : 2 bottles(A and B) of 10L,each containing 10 liter water is given to you.You also have 2 empty bottles of 5 liter and 4 liter respectively.Fill the empty bottles with 3 liter water without wasting any water.
Answer : You can get answer by trial and error method.But rather than that you should try to get answer more intuitively.
You can achieve the solution by posing the problem like this..
1)Get 3 liter water in 5L bottle and Keep 9 liter in one 10L bottle.So you can empty 1 liter from full 4L bottle hence measuring 3 liter in 4L bottle.From above discussion 2 question arises.
1.How to get 3 liter in 5L bottle?
2.How to get 9 liter in 10L bottle(A)?
Answer to 1st question :
To get 3 litter in 5L bottle,you need to get 2 liter in 4L bottle(I hope you got this idea.).
How to get 2 liter in 4L bottle?
Pour 5 liter to 5L bottle from 10L bottle(A). You can get 1 liter in 5L bottle by emptying 5L bottle in 4L bottle.
Now pour 1 liter water from 5L to 4L bottle.(Before that empty 4L to 10L bottle(A). ( 10L bottle(A) now contains 9 liter water.Answer to Question 2 )
Pour 5 liter from 10L bottle(B) (not the one we used before) to 5L bottle. Empty full 5L bottle to 4L bottle(which contains 1 liter water). So,5L bottle contains 2 liter.
Empty 4L bottle to 10L bottle(B). Pour 2 liter to 4L bottle from 5L bottle.
Pour 5 liter from B to 5L bottle.Empty 5L bottle to 4L bottle.So,5L bottle now will contain 3 liter water.
At last,Pour 1 liter water from 4L bottle to 10L bottle(A).
