What is 6.4 × 10−8 mi/day in feet per hour? (1 mi = 5280 ft)
a. 8.11 × 10−3 ft/h
b. 1.408 × 10−5 ft/h
c. 2.909 × 10−10 ft/h
d. 5.05 × 10−13 ft/h