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Ibrahim Hussein of Kenya won the 1992 Boston Marathon (a 26-mile race)
in (about) .8 of an hour less than the winner of the first Boston Marathon in 1897,
John J. McDermott of New York. Find each runner's speed, if McDermott's speed was
(about) .73 times Hussein's speed. (Hint: Don't round until the end of the calculations.)
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Let x be the speed of Ibrahim Hussein of Kenya in the 1992 Boston Marathon, in miles per hour.
Then the speed of John J. McDermott of New York in the first Maraphon in 1897 is 0.87x mph.
The longer time was hours (distance divided by the speed).
The shorter time was hours.
The difference of times was 0.8 of an hour. It gives an equation
- = 0.8
+-----------------------------+
| The setup is complete. |
+-----------------------------+
To solve the equation, multiply both sides by 0.73x. You will get
26 - 0.73*26 = 0.73*0.8x.
Simplify and find x
7.02 = 0.584x
x = = 12.02054795, or 12.021 miles per hour (rounded).
ANSWER. The speed of Ibrahim Hussein of Kenya in the 1992 Boston Marathon was about 12.021 miles per hour.
The speed of John J. McDermott of New York in the first Maraphon in 1897 was about 0.87*12.021 = 10.458 miles per hour.
Solved.