## August 11, 2009

### Golo is locked in a cave !!!

Golo is locked in a cave. He is having 2 vessels with him (5ltr & 7ltr).
The gate of the cave will open only when there are exactly 6 litres on
the handle. He can take as much water as he want from the nearby
water well. How he can make combinations such that the 7 ltr vessel
will have exactly 6 liters of water?

Follow the numbers in refilling the 5-ltr vessel emptying the 7-ltr vessel.

7ltr 5ltr
0 0
0 5
5 0
5 5
7 3
0 3
3 0
3 5
7 1
0 1
1 0
1 5
6 0

Secret Squïrrel said...

This is the other way (slightly quicker)

7L 5L
0   0
7   0
2   5
2   0
0   2
7   2
4   5
4   0
0   4
7   4
6   5

philofsci said...

No no no...

All Golo must do is register exactly 6 L on the scale.

Therefore he simply fills the 7 L and DRAINS it verrry slowly by slightly uncorking the bottom (see picture) and he will eventually reach exactly 6 L at some point. (the runoff can be collected in the 5 and will be 1 L)

When he does... BAM! The gate flies open.

achi said...

take 5 litre water in 5 ltr vesel,and pour it to 7 ltr vessel...then repeat that step one more...then 1 ltr water will remain in 5ltr vessel.remove water from 7 liter vessel and pour this 1 litre(in 5 ltr vessel)into 7 litre vessel.again take 5 ltr water into 5 ltr vessel pour it in 7 litre vessel.
then it contains 6 litre water
achi

Secret Squïrrel said...

@philofsci - I missed you ;-) I thought for a second you were doing an Evan but your solution is really nice. Perhaps it would be even easier if you just put the 7L vessel on the scale-switch, poured in 5L and then slowly poured in some more water until the switch activated, or better yet, just lightly put your fingers on the jug and slowly increased the pressure since this is what the scale is actually measuring.

@achi - when you pour the second lot of 5L into the 7, 3L will remain in the 5L jug (5+5-7=3).

Yaffar said...

a = vessel 7Lt
b = vessel 5Lt

1. fill a
2. put 5 Lt from a in b (a has 2lt, b has 5lt)
3. empty b
4. put 2Lt left on a into b
5. fill a (again)
6. pour into b with 3Lt from a until fill b (4Lt are left on a)
7. empty b
8. pour the 4Lt left on a into b
9. fill a
10. pour last 1Lt from a into b until fill it
11. Et voilá; a has 6 Lt exactly.

Put the a vessel over the switch, and if it does not open the door, then someone is lying you, cruelty... jaja

Pierce said...

5l 7l
0 0
0 7
5 2
0 2
2 0
*Golo takes a rock and marks the 2ltr mark on the 5ltr jug
2 7
5 4
0 4
2 4 *fills 5 ltr to his mark
0 6

Babu vincent said...

5ltr | 7ltr

5 7

5 0

0 5-->

5 5

3 7-->

3 0

0 3-->

3 7

5 4<--

0 4

4 0<--

4 7

5 6(ltr.)

Anonymous said...

Awesome post. Do you mind if I ask what your source is for this information?