Save the Caveman

[LadyWolf]

I was going to post a cute little cartoon done up in an Excel file but found out that there was something in it that wanted to access the internet... I'd rather not share spyware sooo... I'll recount the puzzle here, sans cute cartoon:

Golo is locked in a cave. All he has is a 7 liter container, a 5 liter container, and access to water. The gate of the cave will only open when the 7 liter container is filled with exactly 6 liters on a pressure sensitive handle.

What are the steps you would take to save Golo?

[TonyE]

Good morning Lady Wolf

Spoiler

Fill 5 litre container
Pour it into 7 litre container
Fill 5 litre container again
Pour what you can into 7 litre container, leaving 3 litres in the 5 litre container
Empty 7 litre container
Pour remaining 3 litres from 5 litre container into 7 litre container
Fill up 5 litre container & pour what you can into 7 litre container, leaving 1 litre in the 5 litre container
Empty 7 litre container and tip the 1 litre into it.
Fill up 5 litre again & pour into 7 litre container, which gives 6 litres in the 7 litre container

[mbarron]

My go at it - haven't peeked at TonyE's solution (yet)

Spoiler

5 into 7
5 into 7 - 3 remains in 5
dump 7
fill 7 with 3 from 5
fill 7 rest of the way with 4 liters from 5 - 1 remains in 5
dump 7 fill with 1 from 5 - add 5 more

[LadyWolf]

Very good kids!!

You both had the same solution... there is another... anyone have that one?

[mbarron]

Another solution:

Spoiler

7 into 5 - 2 remain - dump 5
2 into 5
7 into 5 - 4 remain - dump 5
4 into 5
1 from 7 leaving 6

[LadyWolf]

Good job! Golo says

[AlanMiller]

I recall we were given a similar problem to solve in primary school, using actual cylindrical plastic barrels (probably rated in gills back then). I solved the problem by using half measures which I obtained by pouring out until the base of the cylinder became just visible at the water line inside. They thought there was something wrong with me... probably correct.

Alan

[LadyWolf]

A similar problem faces Bruce Willis and Sam Jackson's characters in Die Hard III.
http://www.math.tamu.edu/~dallen/hollyw ... iehard.htm

[pi-eater]

Very good kids!!

You both had the same solution... there is another... anyone have that one?

Spoiler

Fill 7
Pour into 5, 2 left in 7
Empty 5
Pour the 2 from 7 into 5
Fill 7
Fill 5 from 7, 4 left in 7
Empty 5
Pour the 4 from 7 into 5
Fill 7
Pour 1 from 7 to fill 5, 6 left in 7