第18题: [单项选择]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 参考答案:A 答案解析: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)/