Starting at home, Ishaan traveled uphill to the grocery store for 12 minutes at just 15 mph. He then traveled back home along the same path downhill at a speed of 30 mph.
What is his average speed for the entire trip from home to the grocery store and back?
12 minutes at 15 mph covers 3 miles to the store
3 miles /30mph = .1 hr travel time coming home (6 minutes)
6 miles / (12 minutes + 6 minutes) = 6 /18 = 1/3 miles / minute = 20 m/hr average