A hospital is moving from 8-hour shifts for its lab techs to 12-hour shifts. Instead of working

Question:

A hospital is moving from 8-hour shifts for its lab techs to 12-hour shifts. Instead of working five 8-hour days, the lab techs would work three days on and four days off in the first week followed by four days on and three days off in the second week, for a total of 84 hours every two weeks.
Because the peak demand times in the hospital appear to be between 5 A.M. and 7 A.M. and between 5 P.M. and 7 P.M., four 12-hour shifts will be arranged according to the table at the top of p. 109.

The shift pay differentials are based on the most and least desirable times to begin and end work. In any one week, techs on shift A might work Sunday through Tuesday, while techs on shift A (alt) would work at the same times but on Wednesday through Saturday. In the following week, techs on shift A would work Sunday through Wednesday, while techs on shift A (alt) would work the corresponding Thursday through Saturday. Therefore, the same number of techs would be scheduled for shift A as for shift A (alt).
The requirements for lab techs during the 24-hour day are shown in the following table. What is the most economical schedule for the lab techs?