An Efficiency Study of the Morning Shift at a Certain $f ( x ) = - x ^ { 3 } + 5 x ^ { 2 } + 16 x$

Multiple Choice

An efficiency study of the morning shift at a certain factory indicates that an average worker who arrives on the job at 8:00 A.M.will have assembled $f ( x ) = - x ^ { 3 } + 5 x ^ { 2 } + 16 x$ transistor radios x hours later.How many radios will such a worker assemble between 10:00 and 11:00 A.M.?

A) 18
B) 20
C) 22
D) 15