George Bailey and the Extra-Strength Rogaine

Aug 06, 2011

A pharmacist has 10 bottles of extra-strength Rogaine. One bottle is defective. A regular pill weighs 5 grams, while the faulty pills weigh 6 grams each.

The mean old pharmacist tells his assistant, George Bailey, to weigh a pill from each bottle to find the bad batch. But George is in a hurry because he has a date in five minutes. He figures out which bottle is faulty by using the scale only one time. How does he do it?
Here's the answer. George takes one pill from the first bottle, two from the second, etc. He ends up with 55 pills, which should weigh 275 grams (55 pills times 5 grams). If they weigh 276 grams, he has one faulty pill, and he knows it's from bottle #1! If they weigh 278 grams, he has three bad pills from bottle #3, etc.

Sadly, he failed to impress his date. (Maybe it had something to do with the Dodge Dart he was driving.)

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