so just find circumference is
circumfernce=2pir or pid
so diameter 2.5 ft
just for this problem aprox pi=3.14 so
c=pid
c=3.14(2.5)
c=7.85
a. 7.85 ft
b. how many times revolution till one mile (5280)
so
7.85 times x revolutions=5280
divide both sides b y7.85
x revolutions=672.61
round up so we complete the mile (about how many times..)
673 is the answer
a. 7.85 ft
b. 673 times