问题
单项选择题
In order to compute the probability of completing a project on time, the standard deviations (SD) of each activity must be known. These can be calculated using the following expression ______.
A) SD=(b-a)/6
B) SD=b-a/6
C) SD=(a-b)/6
D) SD=(b-a)/12
Note: The definitions of a=most optimistic time and b=most pessimistic time. Use the following information for questions 10 and 11 for the following is duration data related to an activity in a time scale network.
Optimistic time=a=10 days
Pessimistic time=b=20 days
Most likely time=m=12 days
答案
参考答案：A
解析：为了计算按时完成项目的概率，必须知道每个活动的标准方差。可以通过______计算相应的方差。
A) SD=(b-a)/6
B) SD=b-a/6
C) SD=(a-b)/6
D) SD=(b-a)/12
注意：定义a=最乐观时间，b=最悲观时间。使用以下的条件来解答第10和第11题。
乐观时间=a=10天
悲观时间=b=20天
最可能时间=m=12天