Can Mary safely water a plant if it must be watered with exactly 8 liters of water exactly once a day from only one vessel and all she has is a 7-liter jug and a 10-liter jug?

Answer 1

She has to figure out a way to accurately get eight liters in the 10-liter jug. And here's how she would do it. She fills the 7-liter jug with pond water and dumps its contents into the 10-liter jug. So the larger one has seven liters and the smaller is empty. She then refills the smaller and uses it to top off the larger one, which leaves four liters in the smaller one. Next, she dumps the full 10-liter jug back into the pond (why waste water?) and then empties the contents of the smaller one into the larger one, which means there are now four liters of water in the larger jug. So far, so good She refills the smaller jug from the pond and once again tops off the larger jug, which leaves just one liter in the smaller one. Next, she dumps the larger one back into the pond, transfers the one liter from the smaller to the larger, fills the smaller to the top, and then pours it all into the large one, which makes a total of eight liters in the larger jug. Simple! LOL Mary happens to notice a sharp rock on the ground. She first pours 7 liters of water into the big jug. She then refills the 7 liter jug and tops off the 10 liter jug, leaving 4 liters in the 7 liter jug. She uses the sharp rock to mark the 7 liter jug. After she empties the 10 liter jug, she fills the 7 liter jug to the line and dumps it into the 10 liter jug twice.