Answer:
13.63 miles per hour
Explanation:
100 yards / 15 sec converted to miles per hour
100 yards x 60 sec x 60 min x 1 mile = 13.63 miles/hr
15 sec 1 min 1 hr 1760 yards
the mistake on Mrs Dukes is the conversion from miles to yards.
1 mile = 1760 yards NOT 5280 yards