Brain Teasers
Jugs
You've got a 4 liter jug and a 9 liter jug.
You've got a pool of water.
What is the fewest number of steps it takes to come up with exactly 6 liters of water?
No, you cannot pour some water into the 9 liter jug and then guess. Nor can you fill each jug up half way or something. You have to be exact. A step is defined as putting water into a jug (not emptying). For instance, filling the 4 liter jug and then pouring it into the 9 liter jug is 2 steps.
You've got a pool of water.
What is the fewest number of steps it takes to come up with exactly 6 liters of water?
No, you cannot pour some water into the 9 liter jug and then guess. Nor can you fill each jug up half way or something. You have to be exact. A step is defined as putting water into a jug (not emptying). For instance, filling the 4 liter jug and then pouring it into the 9 liter jug is 2 steps.
Hint
It's under 10.Answer
The full answer is as follows:1. Fill up the 9 liter jug from the pool.
2. Fill up the 4 liter jug from the 9 liter jug (leaving 5 liters in the 9 liter jug).
3. Empty the 4 liter jug into the pool and fill it again from the 9 liter jug (leaving 1 liter in the 9 liter jug).
4. Empty the 4 liter jug into the pool and put the 1 liter from the 9 liter jug into the 4 liter.
5. Fill the 9 liter jug from the pool.
6. Fill up the 4 liter jug from the 9 liter jug. There was 1 liter in the 4 liter jug, so 3 liters will fill it. This leaves, in the 9 liter jug, exactly 6 liters.
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Comments
Hey that was a good one I almost submitted one just like this but with 3 and 5 liter jugs. Good job!
I beg to differ, you could:
1) Fill the four litre jug.
2) Pour into the nine litre.
3) Fill the four litre one halway, which can be judged without guessing by leaning it on its side and seeing if it touched both corner and nothing else.
Thats only three steps, and it work just as well.
1) Fill the four litre jug.
2) Pour into the nine litre.
3) Fill the four litre one halway, which can be judged without guessing by leaning it on its side and seeing if it touched both corner and nothing else.
Thats only three steps, and it work just as well.
Trot, that wouldn't work for all shape jugs (think of jug that's asymmetrical in every direction). It wouldn't work very well for jugs you couldn't see through either.
What the teaser *doesn't* specify is that you must have the 6 litres in the 9 litre jug at the end. You could fill the 9 litre jug, empty out 4, then empty out the remaining 5 into whatever receptacle you needed the final 6 litres in. Then you refill the 9, empty out 4 twice, and pour the remaining 1 into the final receptacle.
What the teaser *doesn't* specify is that you must have the 6 litres in the 9 litre jug at the end. You could fill the 9 litre jug, empty out 4, then empty out the remaining 5 into whatever receptacle you needed the final 6 litres in. Then you refill the 9, empty out 4 twice, and pour the remaining 1 into the final receptacle.
that was fun
That was a good one! In response to the comment about filling halfway, the teaser specifies that this is not an option. Plus, the comment about not working for all jugs is correct. Very nicely done!!
That was easy, I love these logic teasers.
pretty good.
I like rocks.
Mar 14, 2006
Two quick comments:
1) On using a "third receptacle" the teaser states that you have two jugs. So one must assume there is no third receptacle3 available. (For if you could assume that, you might as well assume that it was a 6 gallon jug!)
2) Somehow, in all of this, the answer to the question is never revealed! The question was "how many steps does it take?" The answer: 6!
1) On using a "third receptacle" the teaser states that you have two jugs. So one must assume there is no third receptacle3 available. (For if you could assume that, you might as well assume that it was a 6 gallon jug!)
2) Somehow, in all of this, the answer to the question is never revealed! The question was "how many steps does it take?" The answer: 6!
Ya iv heard this one it is a good one
Hm. That was the easiest of the type I've ever encountered. I do like these, though...
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