November 12, 2013
Problem of the Week
for Tuesday, November 12
Your uncle Pascal has returned from his trip to the South Seas with a collection of some very colorful paper money. "It is curious," he says, "that in this collection, whenever there is a picture of a woman on the front of the bill, there is always a picture of a pyramid on the back." He puts four bills on the table. The two bills face-up feature a woman on one and a man on the other, and the two face-down bills feature a pyramid on one and a sphere on the other. Which bill(s) do you need to turn over to see if your uncle is telling the truth?