5. The following table provides inton about a projec Time Activity Tu Show ES, E

Question

5. The following table provides inton about a projec Time Activity Tu Show ES, EF. LS ve LF values and calcula total project lergth? (20 points) The results of u time study is given in the following bhe acti vity slacks. What are the critical path and the 6. able. erformance rating Westinghouse results) Work element bservation time P min.) correct equipment old equipmen 13 67 +8+3,+2, +2 14 12 15 116 33.2 nstall new equipment Company is working net 420 mins in S-hour shuits. a) Calculate the standars time for the process. (10 points) b) For each work element are the number of observations sufficient with absolute error in (c- 5% and confidence level at 95%? If not, how many more are needed? ( 10 points) error in (+X- 7. Machines assigned to an operator where the average machine runs 70% of the time and down 30% of the time. The analyst estimates that 8 machines should be assigned to operator. a) What is the probability that at least 2 machines are down? (10 points) b) Suppose that at most 2 machines down. For this situation; If you want to take sample keeping the margin oferor in 5% and confidence level at 95.4%, how many observations are needed? ( 10 points)

Explanation / Answer

Please find below answer to question no 5 :

The precedence diagram of activities as follows :

The possible paths and their corresponding durations as follows :

A-E-G-H = 17

B-D-G-H = 15

Out of above , the path A-E-G-H has the longest duration and hence forms the critical path.

It is also to be noted that project duration is same as duration of critical path . Therefore , total project length is 17

It is to be noted that SLACK for all activities lying on critical path are ZERO . Therefore , Slacks for activities A, E,G and H are ZERO

Slack of activities B as well as D = Duration A-E-G-H – Duration B-D-G-H = 17 – 15 = 2

Slack of activity C as well as F = Duration A-E-G-H – Duration A-C-F-H = 17 – 16 = 1

Slack is defined as :

Slack = LS ( Late start ) – ES ( Early Start)

Slack = LF ( Late Finish ) – Early Finish ( EF )

The values of ES, LS , EF and LF for each activities are presented in below table :

Early Start ( ES )

Early Finish ( EF )

Late Start ( LS)

Late Finish ( LF)

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