Answer
(a) The length is more than one mile.
(b) The length is less than one mile.
Work Step by Step
(a) Convert the length of the bridge from feet to miles by dividing by the number of feet per mile.
$8981 \div 5280 = 1.7$ miles, so the length is more than one mile
(b) Convert the length of the middle span from feet to miles by dividing by the number of feet per mile.
$4200 \div 5280 = 0.795$ miles, so the length is less than one mile