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Ten-year-old Timmy went on a trip to the coast with his parents. Timmy hated the coast. It stank; sand got in places; fleas liked to bite him; seagulls stole his food. Tim would much rather do math.
On the trip up to the coast his mother drove. She was a very safe driver. The coast was exactly 120 miles away from his home, and his mom drove at 40 mph the whole way there. Timmy was miserable.
His dad drove on the way back, but he wasn't nearly as safe as Tim's mom, so they went 60 mph the whole way back. They both took the same 120 mile route.
Now Timmy started doing some math. He figures it was 120 miles up and back so that's 240 miles total. Since they went 40 mph up, and 60 mph back, their average speed was 50 mph. So, their total travel time should have been 4.8 hours, but Timmy had kept track of the time and they drove for 5 hours. He was positive that it was 5 hours. It took Timmy 30 minutes to figure out why the times didn't match.
How long will it take you?
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