Iron has a density of 7.87 g/cm^3 . What mass of iron would be required to cover a football playing surface of 120 yds x 60 yds to a depth of 1.0 mm? (1 inch = 2.54 cm; 1 lb = 453.6 g)

a. 1.0×105 lb
b. 6.4×104 lb
c. 6.8 x 103 Ib
d. 4.7 x 10 lb
e. 3.7×108 lb