Since the actual data and scatter plot are not provided, I cannot compute the exact profit for the 18th month. However, the general approach would be to use the fitted model to calculate the profit for \( t = 18 \) and check if it meets the goal of \$20,000 (or 20 in thousands of dollars). If the model predicts a profit of 20 or more, the goal is achieved. If not, further analysis or adjustments may be needed.