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Glass of Water Puzzler

Two Glasses of Water

 

Confused by the answer to Ray's water-in-the-glasses puzzler? You weren't alone.

 

Here's what Ray posed:

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?

Here's how Ray solved the puzzler.

First, fill the 9 ounce glass with water.
Next, pour the water in the 9 ounce glass into the 4 ounce glass, until it is full. This leaves 5 ounces in the 9 ounce glass.
Now empty the 4 ounce glass.
Now, fill the 4 ounce glass, using the remaining water from the 9 ounce glass. Once the 4 ounce glass is filled, you'll be left with just 1 ounce of water in the 9 ounce glass.
Empty the 4 ounce glass of water again.
Transfer the 1 ounce of water from the 9 ounce glass into the 4 ounce glass.
Fill the 9 ounce glass with water.
Pour water from the 9 ounce glass into the 4 ounce glass, until the 4 ounce glass is full. Guess what? Since the four ounce glass already has 1 ounce of water in it, it will only take an additional 3 ounces of water.

Guess how much that leaves in the 9 ounce glass? You got it--6 ounces.

Congratulations, you're finished!

drink

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