Archived Stumpers (with solutions)
STUMPER #1.8: TIME TEASERS
(Did you solve something differently? There's almost always more than one way to solve
a math problem. Sometimes there's even more than one correct solution!)
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1. Once Around
____At what time each day does the hour hand on an analog clock complete its first full circle?
2. Equal Parts
____Use two lines to divide the the clock’s face into three parts, so that the sum of the numbers in each of those three parts is the same.
3. Bridge Crossing
__ Four people need to cross a bridge on a dark night. They have only one flashlight for the group. No more than two can cross at a time, and no one can cross unless one member of their group has a flashlight. A group can never cross faster than its slowest member. Annie can cross in one minute; Bob can cross in 2 minutes; Claire can cross in 5 minutes; and Doug can cross in 10 minutes. How can the whole group get to the other side in exactly 17 minutes?
Annie and Bob cross together (2 minutes); Bob goes back (2 minutes); Claire and Doug cross together (10 minutes); Annie goes back (1 minute). Annie and Bob cross together (2 minutes) for a total of 17 minutes.