Water Bottles

Logic Level 2

You have two water bottles, one with the capacity to hold 3 gallons of water, and the other, 5, and an endless supply of water.

How many moves does it take for you to get 4 gallons of water, using just those three items?

(Note: filling a bottle counts as a move, as does placing the liquid from one bottle into the other)

6 7 5 8

1 solution

Vicky Souza
Dec 31, 2014

There are 8 moves to be made:

Fill up the 3-gallon bottle
Place the liquid into the 5-gallon bottle
Fill up the 3-gallon bottle again
Fill the remaining 2 gallons of the 5-gallon bottle with the full 3-gallon bottle
Empty the 5-gallon bottle
Place the remaining 1 gallon into the 5-gallon bottle
Fill up the 3-gallon bottle once more
Place the liquid into the 5-gallon bottle

Hey Vicky, how about this..

$1$ . Fill up 5-gallon bottle.

$2$ . Transfer water from this to 3-gallon bottle, till water is filled up to brim.

$3$ . Throw the water in 3-gallon bottle.

NOTE : Now 2-gallon water is left in 5-gallon bottle.

$4$ . Transfer the 2-gallon water remaining in 5-gallon bottle to the empty 3-gallon bottle.

$5$ . Fill 5-gallon bottle.

$6$ . Transfer the water from 5-gallon bottle to 3-gallon bottle till 3-gallon bottle is filled.

After these $\boxed{6}$ steps, 4-gallon water will be left in 5-gallon bottle.

K V Shenoy - 6 years, 5 months ago

I did it the same way, except in your step 2, I counted transferring the water and emptying the 3-gallon bottle as two different steps.

Jon Haussmann - 6 years, 5 months ago

Thanks, I have updated the answer to 6.

I agree that emptying the 3-gallon bottle should count as another step.

Calvin Lin Staff - 6 years, 5 months ago

@ Jon Thanks for pointing out. Edited.

K V Shenoy - 6 years, 5 months ago

i didnt know v can empty a bottle .....

Ganesh Ayyappan - 6 years, 5 months ago