If a person uses about 4 calories to fuel a minute of walking, and it takes about 20 minutes to walk a mile, approximately how many miles must a person walk to utilize the energy in ("burn") a pound of fat?

43.75 miles must a person walk to utilize the energy in ("burn") a pound of fat.

Explanation:

3,500 calories are present in 1 pound of the fat.

Thus, given that:

4 calories are burnt in 1 minute of walking.

So,

1 calories are burnt in 1/4 minute of walking.

Or,

1 calories are burnt in 0.25 minute of walking.

Thus,

3500 calories are burnt in 0.25*3500 minutes of walking

Minutes of walking needed to burn 3500 calories = 875 minutes.

Also, given that:

20 minutes of walking covers 1 mile.

1 minute of walking covers 1/20 mile.

So,

875 minutes of walking covers (1/20) * 875 mile.

43.75 miles must a person walk to utilize the energy in ("burn") a pound of fat.