Answer:
The new mean annual salary (including the bonus and raise) for the employees is $37790.
Explanation:
new salary Y = $4000 + 1.09X
new mean annual salary E(Y) = $4000 + 0.09*E(X)
= $4000 + 1.09*31000
= $37790
Therefore, The new mean annual salary (including the bonus and raise) for the employees is $37790.