Question: Marcos has to get across a 5 mile lake in his speedboat in 10 minutes so he can make it to work on time. How fast does he need to go in miles per hour to make it? Think carefully first, then make a decision:
10 minutes for 5 miles means 10 minutes / 5 miles = 2 minutes / mile. 1 hour is 60 minutes so 60 minutes / hour / 2 minutes / mile = 30 miles / hour. So the answer is 30.