I only need 2.9 which I can't figure out, it goes with the graph from 2.8. Thank you!

Required Explain to Joel why this unit cost is not useful in predicting total costs for the coming year. 2.7 (LO 1) Cost behavior The Boeing Company produces commercial aircraft. The following pas- sage is taken from Management's Discussion and Analysis, included in Boeing's 2005 Annual Report. Commercial aircraft production costs include a significant amount of infrastructure costs, a portion of which do not vary with production rates. As part of its accounting practices, Boeing spreads the fixed infrastructure costs over the "accounting quantity" for each type of airplane. The accounting quantity is the estimated number of planes that will eventually be produced. At the end of 2005, Boeing's accounting quantity for the 737 Next-Generation plane was 2,800. At the end of 2011, the accounting quantity for this plane had risen to 6,200, and to 11,400 at the end of 2017. Required a. What effect would this change in accounting quantity have on the total fixed infrastructure cost of the 737 Next-Generation plane? b. What effect would this change in accounting quantity have on the unit cost of the 737 Next- Generation plane? 2.8 (LO 2) Scattergraphs Stratton, Inc., has collected the following information on its cost of electricity: Machine Total Hours Electricity Costs January 510 $240 February 540 $300 March 360 $205 April 450 $215 May 660 $290 June 690 $300 July 340 $180 August 520 $260 September 240 $120 October 750 $340 November 840 $360 December 600 $320 Required a. Prepare a scattergraph of Stratton's electricity costs for the year. Plot the total electricity cost on the y-axis. Draw a line that you think best represents the electricity cost function. Be sure that the line runs through at least one of the data points. What is the equation of the line you drew in part (a)? c. What is the expected electricity cost when 750 machine hours are used? d. Why does your answer to part (c) differ from the actual cost for the month of October, when 750 machine hours were used? 2.9 (LO 2) High-low method Refer to the data in Exercise 2-8. Required a. Using the high-low method, compute the variable cost of electricity per machine hour. b. Compute the total fixed cost of electricity. c. Represent the electricity cost function in equation form. d. What is the expected electricity cost when 750 machine hours are used? e. Why does your answer to part (d) differ from the actual cost for the month of October, when 750 machine hours were used? 2.10 (LO 2) High-low method After graduating from dental school two years ago, Dr. Lauren Farish purchased the dental practice of a long-time dentist who was retiring. In January of this year she had to replace the outdated autoclave equipment she inherited from the previous dentist. Now, as she is prepar- ing her budget for next year, she is concerned about understanding how her cost for sterilizing her dental instruments has changed. She has gathered the following information from her records: Month Number of Instruments Used Total Autoclave Cost 850 $7,600 January 6,800