I would like to deduce

**standard deviations and their associated %**and make a list to memorize from the below question from a Mock Exam.

Can I say that...

1 Standard Deviation = 68%

2 Standard Deviations = 95%

3 Standard Deviations = 99%

Do correct me if I am wrong. Thanks.

QUESTION

If you are given that the expected value for your project duration estimate is 627 days, and the most likely duration estimate is 575. The standard deviation is 14. Which of the following statements is true?

A. You have 68 percent confidence that the project duration is between 547 days and 603 days.

B. You have 95 percent confidence that the project duration is between 547 days and 603 days.

C. You have 95 percent confidence that the project duration is between 613 days and 641 days.

D. You have 99 percent confidence that the project duration is between 585 days and 669 days.

MODEL ANSWER

99 percent confidence level is determined by adding and subtracting

*to the expected value. Therefore, the range of dates for this question is 585 days to 669 days.*

**three standard deviations**