Julie travels from A to B at 2 minutes per mile and returns over the same route at 2 miles per minute. Find her average speed, in miles per hour, for the entire trip.
She travels from A to B at 30 miles per hour (60 minutes for 30 miles = 2 minutes per mile).
She travels from B to A at 120 miles per hour (2 miles per minute for 60 minutes).
We can pick a distance that works well with both 30 and 120 such as 120 miles.
From A to B at 30 mph, it will take her 4 hours to go 120 miles.
From B to A at 120 mph, it will take her 1 hour to go 120 miles.
Total distance = 120 + 120 = 240 miles
Total time = 4 + 1 = 5 hours
Average speed = (Total distance)/ Total time = 240 miles / 5 hours = 48 mph
