SOLUTION: Tom can run 5 miles in 1 hour less than the time required for David to run 4 miles. If tom is 4 mph faster than David, how many hours does each man run?
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Question 895054: Tom can run 5 miles in 1 hour less than the time required for David to run 4 miles. If tom is 4 mph faster than David, how many hours does each man run? Answer by lwsshak3(11628) (Show Source):
You can put this solution on YOUR website! Tom can run 5 miles in 1 hour less than the time required for David to run 4 miles. If tom is 4 mph faster than David, how many hours does each man run?
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let x=David's speed
x+4=Tom's speed
Travel time=Distance/speed
..
(4/x)-5/(x+4))=1
lcd:x(x+4)
4(x+4)-5x=x(x+4)
4x+16-5x=x^2+4x
x^2+5x-16
solve for x by quadratic formula:
a=1, b=-5, c=-16
ans:
x≈-7.2 (reject)
or
x≈2.2
x+4≈6.2
..
4/2.2≈1.8 hrs
5/6.2≈0.8 hrs
how many hours does each man run?
Tom:0.8
David:1.8
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