Question 170774
it says there were no marks but I assume they themselves can mark the pail.  The boy with the 4 liter pail needs to fill his pail to the top and fill the 9 liter pail twice....this would make 8 liters leaving it  1 liter from the top....I would then mark the 9 liter pail at the 8 liter mark. Next, I would have the 4 liter boy fill the 9 liter pail to the top. Then making sure the 4 liter pail is totally empty I would pour water from the 9 liter pail into the 4 liter pail until the 9 liter pail is back to the 8 liter mark that was made. This would mean you poured off 1 liter into the 4 liter pail. Now  mark the 4 liter pail at the 1 liter mark....Then empty the 4 liter pail totally out again.  Now take the 8 liters that remain in the 9 liter pail and pour it into the 4 liter pail until the 1 liter mark is reached....thus leaving 7 liters in the 9 liter pail.
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then if I was the 9 liter boy I would fill the 4 liters boy with as much water as possible so I wouldnt have to do all the work..lol

Dang it I started with the wrong pail.......lol