John completed the risk analysis and he knows that the expected value is 100 days with a standard deviation of 12 days. John can be approximately 95% certain that the activity will take between:
A. 88 and 112 days
B. 64 and 136 days
C. 94 and 106 days
D. 76 and 124 days
D: There is a 95% probability that the work will finish within plus or minus two standard deviations. The expected value is 100, and the standard deviation times two is 24, so the activity will take between 76 and 14 days.