I have three jug whose capacity are 8 lt.,5 lt. and 3 lt. and no one jug is calibrated then how can I divide 8 lt. water in two equal parts.

Here is the answer:

Fill the 5 ltr. Jug with water and then pour 3 ltr. In the jug having capacity of 3 lts. So 5 lt jug will have 2 lts in it.
Now empty the 3 lts jug and fill these 2 lts in that. The 3 ltr jug is still having the capacity of 1 ltr more.

Again fill the 5 ltr jug with water and pour 1 ltr to 3 ltr jug. Now the 5 ltr Jug will contains 4 ltr in it.

Put these 4 ltr water in 8 ltr Jug and follow the same procedure to fill the 5 ltr with 4 ltr water.

Thanks
Punit

8ltr 5ltr 3ltr
------------------------------------
8 0 0
3 5 0
3 2 3
6 2 0
6 0 2
1 5 2
1 4 3
4 4 0

Done

Hi freiend , this is a water jug problem, and avsant had given already correct anwser i want to add some thing in to it. always in water jug problem must be mind that fill one of the jug that one is middle capacity and in second step fill the lowest capacity jug then drop this value to largest and then you can see you got easyly soultion...
Might be this steps is not standarized ,but its works freiend and even i haven't fill any problem in water jug problem

8litre 5litre 3litre
-----------------------
8 0 0
3 5 0
3 2 3
6 2 0
6 0 2
1 5 2
1 4 3
4 4 0