The average number of hours can be calculated using the following rule:
average number of hours = total number of hours / total number of weeks
total number of hours = 36 3/8 + 41 1/4 + 40 1/2 + 38 3/8 = 313/2 hours
total number of weeks = 4 weeks
Average number of hours per week = (313/2) / (4) = 39 1/8 hour
Based on the above calculations, the correct answer is:
C. 39 1/8 hour