Month: January 2010

Answer to Last Semester’s Newsletter Puzzler

Submitted by Lee Bradley

The Question:
A bartender has a 3 pint glass and a 5 pint glass. A customer walks in and orders 4 pints of seltzer water. Without a measuring cup but with an unlimited supply of seltzer water, how does he get 4 pints in the 5 pint glass? (Hint: The bartender needs 4 pints exactly; you cannot say: “Fill the 5 pint glass 4/5 full.”) There are two possible solutions to this problem.

Solution A
Both “glasses” are empty.
Fill the 3 pint glass.
Pour the 3 pint glass into the 5 pint glass.
Fill the 3 pint glass.
Fill the 5 pint glass from the 3 pint glass, leaving 1 pint in the 3 pint glass.
Dump the 5 pint glass into the sink.
Pour the 1 pint in the 3 pint glass into the 5 pint glass.
Fill the 3 pint glass.
Pour the 3 pint glass into the 5 pint glass.

Solution B
Both “glasses” are empty.
Fill the 5 pint glass.
Fill the 3 pint glass from the 5 pint glass, leaving 2 pints in the 5 pint glass.
Dump the 3 pint glass into the sink.
Pour the 2 pints that are in the 5 pint glass into the 3 pint glass.
Fill the 5 pint glass.
Fill the 3 pint glass from the 5 pint glass, leaving 4 pints in the 5 pint glass.

In some sense, Solution B is better than Solution A because it requires fewer steps and wastes less water!

Correct answers were submitted by Melanie Kelly, Nancy Giudice, Robert Wahl, and David Wright.