Question 1043792
The percentage of a normal distribution that is less than 1 sd above the mean is 0.8413. If that is multiplied by 36, 30.28 months would be expected to have fewer than 9.37 days per month, or rounding to 30 months. This answers the specific question.
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If one recognizes that number of days of leave is an integer, then we would use 9 days per month, and the probability it is fewer than 9 days per month is 0.80, so 28.8 months or 29 months would be the answer.   This answers the reality of what the data mean.