A company provides maintenance service for water-filtration system throughout the city. To estimate the service cost, the company's managers want to predict the repair time necessary for each maintenance request. Repair time is believed to be related to two factors, the number of months since the last maintenance service and the type of repair problem (mechanical or electrical). Data for a sample of 10 service calls are reported in the following table.

Service Months Since Type of Repair Repair Time Call Last Service in Hours Electrical 3.4 Mechanical 2.1 Electrical 4.5 Mechanical 3.9 Electrical 3.7 40 00 1 00 A N O O W N Mechanical 2.5 Electrical 5.8 Mechanical 4.5 Electrical 5.5 10 Mechanical 4.8