Semisphere area is found by
Volume V = (1/2)•(4/3)• (π•r^3)
Diameter of the mode is
D = 2•r = 12.2 ft
Then
r= 12.2/2 = 6.1 ft
Then now find V
V = (4/6) •(π• (6.1^3) = (4/6)•π•( 226.981)
V= 151.3207 • π= 475.38 cubic feets
THEN ANSWER IS
OPTION C) 475.4 ft^3