How can you bring exactly 2 liters of water from a pond when you have only a 7 liter and 4 liter pail?

Question

I need to know how to be able to get 2 liters of water out of a 7 liter pail and 4 liter pail? Have been trying to figure it out for a long time but can't come up with the answer really need help.

Answer 1

fill the 7 liter pail and pour it into the 4 liter pail leaving 3 liters behind.

transfer the 3 liters to the 4 liter pail.

fill the 7 liter pail again and pour it into the 4 liter pail with the 3 liters already in it.

It will take 1 liter and leave 6 liters remaining in the 7 liter pail.

Empty the 4 liter pail.

Transfer the 6 liters into the 4 liter pail leaving behind 2 liters in the 7 liter pail

You have your 2 liters