Not sure where this test started but it has become a basic interview problem solving test that people have been doing for years. I think it was even in a Die Hard movie. I’m sure this ranks right up there with the “Moving Mt. Fuji” project management test that Microsoft used to give people in interviews.
Firstway: Wastes 5 gallons to make 4 Gallons
- fill the 3-gallon jug to the top
- empty the 3-gallon into the 5-gallon jug
- fill the 3-gallon jug again
- empty this into the 5-gallon jug, thus leaving 1 gallon in the 3-gallon jug
- empty the 5-gallon, and then pour the contents of the 3-gallon into the 5-gallon
- Fill the 3-gallon jug, and then emptying it into the 5-gallon jug, giving exactly 4 gallons
Second way: Wastes 3 Gallons to make the 4 Gallons
- fill 5-gallon jug
- empty 5-gallon into 3 gallon, thus leaving 2 gallons in 5-gallon jug
- empty 3-gallon jug
- empty 5 gallon jug into the 3-gallon jug
- fill the 5-gallon jug again
- fill 3-gallon jug to the top, giving 4 gallons in 5-gallon jug.