What is being asked here is to convert the value above from units of yards per second into miles per hour. To do this, we need a conversion factor to multiply to the value for it to be converted to another units. We do as follows:
Conversion Factors
1 mile = 1760 yards
1 hr = 3600 s
3 yd/s ( 1 mile / 1760 yards ) (3600 s / 1 hr) = 10.8 miles per hour