You have 3 unmarked pitchers that hold 6 cups, 10 cups, and 15 cups. The 10 cup pitcher is filled with lemonade, but you have to dilute it so people at the party don't complain that it's too sour. Unfortunately, I have, in the name of logic, broken your only measuring cup.

How can you dilute the lemonade to 20 cups such that all of the lemonade is of equal concentration? You have a sink with unlimited water, but you can't waste any lemonade. Try using as few moves as possible.

pour the 10 cups into the 15-cup pitcher, and fill it with water until it is full. (You now have 15 of the 20 desired cups)  Pour lemonade into the 10-cup pitcher until it is full, then pour the rest into the 6-cup pitcher.  Empty the 10-cup pitcher into the 15-cup pitcher, and fill it to the top with water.  Voila!  20 cups.

Posted by Libby on 2005-08-08 01:51:42