Final answer:
To forecast the 2019 demand using the graphic method, create a scatter plot, calculate the least-squares line equation, draw the line on the plot, and find the correlation coefficient.
Step-by-step explanation:
To forecast the 2019 demand using the graphic method, you need to create a scatter plot of the given data points. Plot the years (x-axis) against the demand (y-axis) for each data point. Then, draw a straight line that best fits the points. The intercept in y represents the point where the line crosses the y-axis.To calculate the least-squares line, you can use regression analysis. This will give you the equation of the line in the form ŷ = a + bx, where a is the intercept and b is the slope of the line. Once you have the equation, you can draw the line on the scatter plot.To find the correlation coefficient, you can use a statistical software or calculator that provides this measure. The correlation coefficient indicates the strength and direction of the relationship between the variables. If the coefficient is close to 1 or -1, it indicates a significant relationship.