2.10 - Using Excel to Use the High-Low Method PROBLEM fter graduating from dental school two years ago, Dr. Lauren arish purchased the dental practice of a long-time dentist who as retiring. She purchased the practice in January of this year nd immediately had to replace the outdated autoclave quipment she inherited from the previous dentist. Now, as she preparing her budget for next year, she is concerned about nderstanding how her cost for sterilizing her dental instruments as changed. She has gathered the following information from er records. Month Number of Instruments Used Total Autoclave Cost January 850 $ 7,600 February 750 6,800 March 920 8,200 April 950 8,600 May 1,150 9,900 June 900 8,100 July 1,050 9,600 August 975 8,700