If I have a bucket of water that holds 4 gallons of water and another bucket that holds 7 gallons of water. The buckets have no markings. How can I go to the well and bring back exactly 5 gallons?

Start with empty buckets, and carry them to the well. (Note that the larger is the 7-gallon bucket, and the smaller is the 4-gallon bucket.) Fill the 4-gallon bucket with water to the top. Empty all...

Fill up the 3 gallon bucket twice and empty the water into the 5 gallon bucket. This will leave you with 1 gallon in the 3 gallon bucket. Empty the 5 gallon bucket and pour the 1 gallon of water from...

1 Liter of water weighs 1 Kg. 5 gallons of water is 18.93 Liters, so 18.93 Kg for the water. I have no idea the mass of the bucket.

You haven't told us how big the bucket is. But even if we knew that, we would have no way of knowing how much water is in it. Maybe it's empty and you're just pulling our chain.

7 bucket 3bucket 0 3 3 0 3 3 6 0 6 3 7 2 0 2 2 0 2 3 5 0