A 160-lb person who runs at 8 mph for 1 hr burns about 840 calories. The same person, walking at 2 mph for 90 min, burns about 240 calories. Suppose a 160-lb person runs at 8 mph for 75 min. How far would the person have to walk at 2 mph in order to burn the same number of calories as burned when running? The person has to walk __________________miles.

A 160 lb individual runs at 8 mph for 1 hour (60 minutes) and burns 840 calories. If this person runs at the same pace for 75 minutes (1.25 hours) he will burn 840 calories (60 min) + 210 calories (15 min), which equals a total of 1,050 calories burned. We obtain the calories burned in 15 min by dividing 840 (calories burned in 60 min) in 0.25 (portion of an hour equivalent to 15 min).

Now this person to burn 1,050 calories walking at a pace of 2mph will have to walk around 6.5625 miles. By walking during 90 minutes (1.5 hours) the person burns 240 calories, and to burn 1,050 calories the would have to walk for 6.6 hours approximately. We get the hours by using the mathematical rule of three: dividing 1,050 calories in 1.5 hours, and multiplying the result by 240 calories.

Finally to calculate the miles the person will have to walk we have to multiply the 6.6 hours by 2 miles he walks per each hour. So the person has to walk around 13.125 miles at 2mph to burn 1,050 calories.