Aug. 20, 2003
A Speedy Palindrome
Sarah checks out the odometer on her car. It reads 14,941 miles. She notices that it reads the same backward as forward.
"I wonder how long it will be before that happens again?" Sarah thought to herself.
To her surprise, in 2 hours the odometer showed a new palindrome number.
What was the number, and what was the average speed of the car in those 2 hours?
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Think about what the next middle digit would be.
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The average speed of Sarah's car was 55 miles per hour.
Here's why: The next palindrome number on Sarah's odometer will be 15,051. That's 110 miles past her current setting of 14,941. If she took 2 hours to go 110 miles, she was averaging half of this, or 55 miles, each hour.
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