A project has a completion time of 24 weeks with a variance of 9 weeks. Assuming

Question

A project has a completion time of 24 weeks with a variance of 9 weeks. Assuming that the project completion time follows a normal distribution, compute the following: 3. a) b) c) The probability that the project will be completed in less than 20 weeks. The probability that the project will be completed in more than 26 weeks. The probability that the project will be completed between 20 weeks and 26 weeks. 20 Sawing Infil 20 20 10 30 PlacementAssmbly Outfill 4. Compute the ES,EFLS, LF and slack for the project network given above.

Explanation / Answer

It is given that Mean of the Project is 24 days and standard deviations is 3 days ( Because variance is 9)

1) Probability of completing the the project within 20 days

P(X<=20) = P(((X-Xbar)/SD)/((20-24)/3)) =

P(z<=-4/3) =

P(Z<=-1.333) =

0.5- Area between 0 to 1.33 in Standard Normal Distribution =

0.5- 0.4082 = 0.918

b) Probability of completing the project within 26 days is P(X<=26) =

P(Z<= (26-24)/3) = P(Z<=0.66666) = 0.5+0.2486 =0.7486

C) P( Completing within 20 AND 26 days) = P(20<=X<=26) = P(-1..333<=Z<=0.6666)

=0.4082+0.2486 = 0.6568

Additional Information:

1)Question on normal distribution is converted to standard normal distribution

I.e. Z= (X-Average)/ SD

2) Calculation of Table Value is from standard Normal Distribution

When Questions is less than and Z is Positive, Probability = 0.5+ table value

When Questions is less than and Z is Negative, Probability =0.5- table Value

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