To support its large fleet, North American Airlines maintains an extensive inventory of spare parts, including wing flaps. The number of wing flaps needed in inventory to replace damaged wing flaps each month depends partially on the number of flying hours for the fleet that month, since increased usage increases the chances of damage. The following table shows both the number of replacement wing flaps needed and the number of thousands of flying hours for the entire fleet for each of several recent months.
(a) Identify the dependent variable and the independent variable for doing causal forecasting of the number of wing flaps needed for a given number of flying hours.
(b) Plot the data on a graph.
(c) Find the formula for the linear regression line.
(d) Plot this line on the graph constructed in part (b).
(e) Forecast the average number of wing flaps needed in a month in which 150,000 flying hours are planned.
(f) Repeat part (e) for 200,000 flying hours.