Consider the Interaction Model $E ( y ) = 3.6 + 1.2 x _ { 1 } + 2.4 x _ { 2 } + .2 x _ { 1 } x _ { 2 }$

Multiple Choice

Consider the interaction model $E ( y ) = 3.6 + 1.2 x _ { 1 } + 2.4 x _ { 2 } + .2 x _ { 1 } x _ { 2 }$ . Determine the change in $E ( y )$ when $x _ { 1 }$ is changed from 6 to 7 and $x _ { 2 }$ is held fixed at 3 .

A) $1.8$
B) $4.2$
C) $10.8$
D) $11.4$