SOLUTION: A man ran 8 miles and walked 6 miles. if he ran 5 mph faster than he walked, and the total time was 2 hours, how fast did he walk?
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-> SOLUTION: A man ran 8 miles and walked 6 miles. if he ran 5 mph faster than he walked, and the total time was 2 hours, how fast did he walk?
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You can put this solution on YOUR website! A man ran 8 miles and walked 6 miles. If he ran 5 mph faster than he walked,
and the total time was 2 hours, how fast did he walk?
:
Let s = his walking speed
then
(s+5) = his running speed
:
Write a time equation, Time = dist/speed
Running time + walking time = 2 hrs + = 2
Multiply equation by s(s+5), results:
8s + 6(s+5) = 2s(s+5)
:
8s + 6s + 30 = 2s^2 + 10s
:
14s + 30 = 2s^2 + 10s
Arrange as a quadratic equation
2s^2 + 10s - 14s - 30 = 0
:
2s^2 - 4s - 30 = 0
simplify, divide by 2
s^2 - 2s - 15 = 0
Factor
(s-5)(s+3) = 0
The positive solution is what we want here
s = 5 mph, walking speed
;
:
Check solution
8/10 + 6/5 =
.8 + 1.2 = 2 hrs
