Answer:
(D) increase of $1 in advertising is associated with an increase of $4,000 in sales
Explanation:
The regression analysis yielded the following equation, with sales (Y in $1000) and advertising (X in dollars):
[tex]Y(X) = 30,000 + 4X[/tex]
The rate of change is 4, which means that for each unit increase in X, there will be a 4 unit increase in Y.
Since X is given in dollars and Y is given in $1000. An increase of $1 in X (advertising) is associated with an increase of $4,000 in Y (sales).
Therefore, the answer is (D).