A man runs to a telephone and back in 15 minutes. His speed on the way to the telephone is 5m/s and his speed on the way back is 4m/s. Find the distance to the telephone.
This is a distance problem so we can use distance = rate x time.
Given: the distance to the telephone is the same as the distance back from the telephone. We also know the two speeds and the total time for the trip.
But first let's convert 15 minutes into seconds: 15*60 = 900 seconds.
So: d = 5(t1) (t1 is the time he took to run to the telephone) d = 4(t2) (t2 is the time he took to come back from the telephone t1 + t2 = 900 or t1 = 900 - t2
