Question on PERT from Mohit Arora book

Submitted by Sirisha.61186 on Sat, 10/08/2016 - 14:31

Question : You have collected a large amount of data in the last 3 weeks. Sampling was accomplished from a population set of over 1000 data sets. The mean for the data set is 50 and a standard deviation of 10. Which of the following is true ?

(a) A value of 11 is within one standard deviation of the mean

(b) 41, 45 and 109 are within the range of values which could be expected about 68% of the time

(c) 38 and 62 are within two-sigma limits 95.45% of the time

(d) Values of 30 and 80 fall within the three-sigma limits

This question is taken from the book '1000 PMP challenge questions' by Mohit Arora. As per the book, the answer is (b)

Could you please help me understand how the answer is (b). Thank you so much in advance.

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muhsin

Mon, 10/10/2016 - 06:00

MEAN=50

SD=10  FOR  ONE SIGMA

RANGE FROM 40 TO 60

SO IF 2 SIGMA MEANS THAT  THE VAULE OF 30 TO 70  WITH THE RANGE.

pmalik

Wed, 10/19/2016 - 13:16

B is incorrect answer. C is the best answer but D is also correct.

To understand the complete explation, you can read an article on PERT and Standard Deviation.

I think you should questions from some reliable sources. You can find about 3500 free question here -  PMP Sample Questions.

Good luck.