Solve the Problem $x$ Radios Is $r ( x ) = 60 x - \frac { x ^ { 2 } } { 10 }$

Multiple Choice

Solve the problem.
-Suppose that the revenue from selling $x$ radios is $r ( x ) = 60 x - \frac { x ^ { 2 } } { 10 }$ dollars. Use the function $r ^ { \prime } ( x )$ to estimate the increase in revenue that will result from increasing production from 100 radios to 101 radios per week.

A) $80.00
B) $50.00
C) $39.80
D) $40.00