Your Porsche's Gas Mileage (In Miles Per Gallon) Is Given $M ^ { \prime } ( x ) = \frac { 5,625 x ^ { - 2 } - 1 } { \left( 5,625 ^ { - 1 } + x \right) ^ { 2 } }$

Multiple Choice

Your Porsche's gas mileage (in miles per gallon) is given as a function M(x) of speed x in miles per hour. It is found that
$M ^ { \prime } ( x ) = \frac { 5,625 x ^ { - 2 } - 1 } { \left( 5,625 ^ { - 1 } + x \right) ^ { 2 } }$ .

Find $M ^ { \prime } ( 55 )$ , $M ^ { \prime } ( 75 )$ and $M ^ { \prime } ( 95 )$ .

A) $M ^ { \prime } ( 55 ) = 0.00004 , M ^ { \prime } ( 75 ) = - 0.00028 , M ^ { \prime } ( 95 ) = 0$
B) $M ^ { \prime } ( 55 ) = 0.00028 , M ^ { \prime } ( 75 ) = 0 , M ^ { \prime } ( 95 ) = - 0.00004$
C) $M ^ { \prime } ( 55 ) = 0.00004 , M ^ { \prime } ( 75 ) = 0 , M ^ { \prime } ( 95 ) = - 0.00028$
D) $M ^ { \prime } ( 55 ) = 0 , M ^ { \prime } ( 75 ) = 0.00028 , M ^ { \prime } ( 95 ) = - 0.00004$
E) $M ^ { \prime } ( 55 ) = 0 , M ^ { \prime } ( 75 ) = 0.00004 , M ^ { \prime } ( 95 ) = - 0.00004$