fill 3 gallon bucket, fill the 5 gallon bucket with the 3 gallon fill the 3 gallon bucket again, fill 2 gallon of the 3 to the 5 gallon one, now there is 1 gallon left in the 3 gallon bucket empty the 5 gallon bucket and fill the 1 gallon into the 5 gallon bucket fill the 3 gallon bucket. now you have 4 gallon water, 1 in the 5 gallon bucket and 3 in the 3 gallon bucket

Place the 3 gallon bucket upside-down inside the 5gal bucket...fill up the 5 gallon bucket and remove the 3 gallon to get the 2 gallons...then repeat. (This is assuming the 3 gallon bucket fits in the 5 gallon bucket.)

Fill the 3 gallon bucket from a full 5 gallon bucket, the remainder will be 2 gallons. Empty the 3 gallon bucket. Put the 2 remaining gallons from the 5 gallon bucket in the empty 3 gallon bucket. Fill the 5 gollon bucket and pour the 5 gallon bucket into the 2/3 full 3 gallon bucket until its full (should be 1 gallon). What remains in the 5 gallon bucket is 4 gallons.

Make it simple the reply is 5 gallon - 3 gallon = 2 gallons that will the difference what remain in the 5 gallon bucket , because the 3 gallon bucket is full, is 2 gallon volume you do it 2 times you have 4 gallons

easy. 5+3 is 8, the avg is 4. fill both buckets up and empty 50 percent from both and you are left with 4 gallons. 2.5+1.5 is 4 gallons.