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A male worker performs a repetitive task with a 12-min work cycle. During each cycle his energy expenditure rate is 7.8 kcal/min for 20% of the time and 5.6 kcal/min for the remaining 80%. How much of a rest break should be allowed at the end of each work cycle if he must work 4.0 hours in the morning and 4.0 hours in the afternoon? Use a maximum time-weighted average energy expenditure rate of 5.0 kcal/min as the standard or recommended level.