What is the average metabolic rate for a boiler maker who is performing maintenance on the boiler during shutdown and works for 3 hours at 3.5 kcal/min, takes a break for 30 min in a sitting position (metabolic rate = 0.3 kcal/min), resumes working on the outside of the boiler for 3.5 hours (metabolic rate = 2.5 kcal/min), then performs administrative work in the area for 1 hour (metabolic rate = 0.4 kcal/min)?