The correct answer is " It depends when the period starts " Option D is correct.
Given that the crew of US submarines work on an 18-hour cycle rather than a 24-hour day. They divide into three ‘watches’, each working for 6 hours, with a meal break for the half hour immediately before and another for the half hour immediately after work. The watches change at 05:30, 11:30, 17:30 and 23:30 Universal Time, no matter where in the world they are.
The total work hours for three days will be
18 x 3 = 54 hours
Since each member has a meal break for the half hour immediately before and another for the half hour immediately after work, that means each member has a total mean break of one hour in a day.
Total time for meal break for three days will be
3 x 1 hour = 3 hours
Total time = 54 + 3 = 57 hours
Total available time in three days will be
24 hours x 3 = 72 hours
Minus the total time from total available time
72 - 57 = 15 hours
The remaining time is not up to 18 hours or more than 18 hours, the crew members that start first two periods will experience more meal breaks than the last period.
The time for meal breaks a member of the crew get in a 72-hour (3-day) period will be between 3 1/2 hours and 4 hours
Therefore, the correct answer is " It depends when the period starts "
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