second part of both confuses me

Trucks artive at the loading dock of a wholesale grocer at the rate of 1.2 per hout. A single crew consisting of two workers can load a truck th about 30 minutes. Crew members receive $10 per hour in wages and fringe benefits, and trucks and drivers reflect an hourhy cost of $61. The manager is thinking of adding another member to the crew. The service rate would then be 2.4 trucks per hour: Assume rates are Poisson, Use Fable 1 and Table 2 10 a. Would the third ctew member be economical? (Round your intermediate and final answer to 2 decimal places.) Answer is complete but not entirely correct. b. Would o fourth member be justifioble if the resulting service capocity were 3 trucks per hour? (Round your intermediate and final answer to 2 decimal places.)