Question

Using PERT, Adam Munson was able to determine that the expected project completion time for the construction of a pleasure yacht is 15 months, and the project variance is 4, the probability that the project will be completed in 16 months is _ (Round to one decimal place)

Answer 1

Answer:

approximately 0.7

Explanation:

Pert Analysis is used to compute/sum up the various variances of a project along its critical path

using PERT

The mean value of project ( estimated project time ) = 15

project variance б = 4

standard deviation = $\sqrt{}$ б = 2

probability that project will be completed on or before 16 months  

= P ( X ≤ 16 )

this means  Z ≤ $\frac{X - 15}{2}$ where X = 16

= Z ≤ 1

using the the normal distribution appendix for the Z value the probability of completing the project in 16 months would approximately be 0.7

Answer 2

Answer:

The probability that the project will finish in 16 months is 0.7.

Explanation:

From the data the mean time is given as  $\mu=15$

The variance is given as $\sigma^2=4$

So the standard deviation is $\sigma=2$

Now the X is given as 16 so

Calculating the z score as

$z=\dfrac{x-\mu}{\sigma}\\z=\dfrac{16-15}{2}\\z=\dfrac{1}{2}=0.5$

So for the z score of 0.5 the probability is given in Excel as

=NORMSDIST(0.5)

=0.69 ≈0.7

So the probability that the project will finish in 16 months is 0.7.