Answer
$8.7$ hrs.
Work Step by Step
Energy in 1 pound: $7.7kcal/1g*454g/1 lb$ = 3495.8 kcal. Time to burn this: $3495.8/400 = 8.7$ hrs
You can help us out by revising, improving and updating this answer.
Update this answerAfter you claim an answer you’ll have 24 hours to send in a draft. An editor will review the submission and either publish your submission or provide feedback.