A shipping company believes that the variation in the cost of a customer’s shipment can be explained by differences in the weight of the package being shipped.

To investigate whether this relationship is useful, a random sample of 20 customer shipments was selected, and the weight (in lb) and the cost (in dollars, rounded to the nearest dollar) for each shipment were recorded.

The following results were obtained:

Weight (x) Cost (y)

8 11 6 8 5 11 7 11 12 17 9 11 17 27 13 16 8 9 18 25 17 21 17 24 10 16 20 24 9 21 5 10 13 21 6 16 6 11 12 20

a. Construct a scatter plot for these data. What, if any, relationship appears to exist between the two variables?

b. Compute the linear regression model based on the sample data. Interpret the slope and intercept coefficients.

c. Test the significance of the overall regression model using a significance level equal to 0.05.

d. What percentage of the total variation in shipping cost can be explained by the regression model you developed in part b?