Calculate the Average Rate of Change of the Given Function $[ 7,8 ]$

Multiple Choice

Calculate the average rate of change of the given function over the interval $[ 7,8 ]$ . $f ( x ) = \frac { x ^ { 2 } } { 7 } + \frac { 15 } { x }$

A) $2 \frac { 7 } { 8 }$
B) $\frac { 8 } { 15 }$
C) $2 \frac { 1 } { 8 }$
D) $1 \frac { 7 } { 8 }$
E) $\frac { 7 } { 8 }$