Find the surface area of a sphere with a circumference of 40 ft. Round to the nearest tenth.

a) 6.4

b) 509.3

c) 245.6

d) 40.5

The circumference of the sphere is calculated through the equation, C = 2πr. Rearranging the equation gives an equation for r which is r = C/2π. Substituting,

r = 40 ft / 2π = 6.366 ft

The equation for the surface area of the sphere is SA = 4πr². Substituting the value of radius,

SA = 4π x (6.366 ft) ² = 509.30 ft²

Thus, the answer is letter B. 509.3 ft².