You have a four-ounce glass and a nine-ounce glass. You have an endless supply of water. You can fill or dump either glass. It turns out that it’s possible to measure six ounces of water using just these two glasses. What’s the fewest number of steps in which you can measure six ounces?
Originally published on December 1st, 2009
January 25th, 2011 | Category: 
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I’m not sure if it’s the fastest but I’d go with
Fill 9, pour into 4, empty 4, pour into 4, empty 4, pour the last ounce into 4, fill 9, fill the last 3 ounces in the 4 glass with 3 from the 9 glass, thus you have only 6 ounces left in the 9 glass.
That’s a total of 8 steps.
You’ve got the idea, Jonathan.
We figured it could be done in six steps, but you seem to have nailed it.
Here’s the RiddleDude’s solution:
Fill the 9 oz and pour it into the 4 oz. Dump the 4 oz and repeat. Now you have one oz in the four. Refill the 9 and fill up the balance of the 4. That leaves 6.
Either way, you’re today’s winner!
Pour 4 oz of water into the 9 oz. Then pour 1/2 of the 4 oz ( 2 oz) into the 9 oz for a total of 6 oz.