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 In January of this year she had to replace the outdated autoclave equipment she inherited from the previous dentist.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 preparing 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: Number of instruments Month used Total autoclave cost January 600 $7,400 February 500 6,500 700 April 9,000 May 7.600 1,000 8,500 1.200 10,000 1,100 9.800 March 7,000 900 800 June July August