15.35 Refer to the Johnson Filtration problem introduced in this section. Suppose that in addition to information on the number of months since the machine was serviced and whether a mechanical or an electrical repair was necessary, the managers obtained a list showing which repairperson performed the service. The revised data follow.

Repair Time in Hours Months Since Last Service Type of Repair Repairperson 2.9 2 Electrical Dave Newton 3.0 6 Mechanical Dave Newton 4.8 CO Electrical Bob Jones 1.8 3 Mechanical Dave Newton 2.9 2 Electrical Dave Newton 4.9 Electrical Bob Jones 4.2 LO Mechanical Bob Jones 4.8 CO Mechanical Bob Jones 4.4 4 Electrical Bob Jones 4.5 Electrical Dave Newton