The distance between two cities is one hundred miles, and a woman drives from one city to the other at a rate of fifty mph. At what rate must she return if the total travel time is three hours and forty minutes?
45 mph
54 mph
60 mph
It takes her (100 mi)/(50 mi/h) = 2 h to get to her destination. She has 1 h 40 min = 100 min for her 100 mi return trip. .. (100 mi)/(100 min) = (60 mi)/(60 min) = 60 mi/h
She must return at the rate of 60 mph to complete the trip in 3 h 40 min.
