Problema Solution

A runner starts at the beginning of a runners' path and runs at a constant rate of 5 mi/hr. Ten minutes later a second runner begins at the same point, running at a rate of 7 mi/hr and following the same course. How long will it take the second runner to reach the first?

Answer provided by our tutors

let


t = the time of the second runner


t + 10/60 = the time of the first runner (since he started running 10 min earlier)


since distance = speed*time and they both ran the same distance we have:


7t = 5(t + 10/60)


by solving we find:


t = 5/12 hr


t = 5*60/12 min


t = 25 min


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the second runner will run 25 minutes to reach the first.