Maths Olympiad Prep

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Number theory Difficulty 2.0 Junior Find the answer

Barney Schwinn notices that the odometer on his bicycle reads 14411441, a palindrome, because it reads the same forward and backward. After riding 44 more hours that day and 66 the next, he notices that the odometer shows another palindrome, 16611661. What was his average speed in miles per hour?

Pick one

Solution

Barney travels 16611441=2201661-1441=220 miles in 4+6=104+6=10 hours for an average of 220/10=(E) 22220/10=\boxed{\textbf{(E)}\ 22} miles per hour.

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Source: NuminaMath-1.5, licensed Apache-2.0. Statement and solution reproduced as published; topic and difficulty added by this site.