Question

The management of Cabinets Unlimited wants to know how long it will take to assemble a new cabinet in their product line. To that end, the Production Manager has identified the following tasks (and task times) that must be accomplished: Task Description A B с D E F G H I Prepare the wheels Mount the wheels Assemble the sides Attach the top Attach the base Insert the shelves Attach the doors Attach the back Paint the unit Task time (minutes) Immediate Predecessor 8 5 15 11 10 5 9 9 15 On the basis of the following information, fill in the column labeled "Immediate Predecessor" in the table above. The wheels are mounted after they are prepared. The top is attached only after the sides are assembled. The base cannot be attached until the sides are assembled and the wheels are mounted. The shelves are inserted after the base is attached. The door cannot be attached until both the top and the base are attached. The back is attached after the doors are attached. The unit is painted after the back is attached and the shelves are inserted. To prepare for the possible project expediting, crash data has been collected as below. (Crash time is the minimum time that can be achieved for each task - tip: it is what you can do and you do not have to crash to the minimum.) Crash Cost per Minute 2 Task Normal time A 8 B 5 с 15 D 11 E 10 F 5 G 9 H 9 1 15 Crash Time 8 5 12 8 8 4 4 2 4 نیا 3 6 15

1)For activity H – Attach the back, what is/are the predecessor(s)? Choose all that apply. C D I H G F E

2)Draw your project network diagram based on the information provided. Based on your network diagram, what is (are) the successor node(s) for activity E? Choose all that apply. I C F G H D

3)What are the critical activities (with zero slack time) for this project? Choose all that apply. Choose all that apply. G H B A D C E I

4)What is the EST of activity E? Round to the nearest integer.

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Answer 1

Based on the given paragraph, we get the predecessor list as shown below:

Activity Description Predecessor A А B C D E F G H Prepare the wheels Mount the wheels Assemble the sides Attach the top Attach the base Insert the shelves Attach the doors Attach the back Paint the unit С B, C E D, E G HF —

Hence, Answer 1) G

We draw the project network diagram as shown below:

Legend EST ID EFT SLK LST DUR LFT 0 А 8 B 13 3 8 3 11 3 8 11 5 16 C 15 25 F 30 0 0 0 15 E 1 16 10 25 14 39 15 5 15 26 5 44 59 44 0 44 15 D 26 G 35 H 44 15 59 Մ|Չ |Ն 26 0 26 35 0 15 11 26 9 35 Сл 9 44

As seen from above, successor nodes of E are F, G, H, I

As seen from above, the activities with 0 salck time are C, D, G, H, I

As seen from above, the EST of activity E = 15

The above network diagram in the form of formulas is shown below for better understanding and reference:

A с D E F H M N P Q R S T U V W 1 B Legend ID EFT 2 3 EST SLK LST 4 DUR LFT А =A6+B8 B =E6+F8 5 6 0 7 =A8-A6 8 =C8-B8 9 =C6 =E8-E6 =G8-F8 8 =E8 5=112 =A10+B12 F =M10+N12 =MAX(G6,C10) E = 10+J12 =112-110 =K12-J12 10 =MIN(M12,M16) =K10 =M12- M10 =O12-N12 =MIN(112, E16) 5 =U14 10 O с 11 =A12-A10 12 =C12-B12 15 13 14 15 =MAX(010,914) 1 =U12+V14 =U14-U12 =W14-V14 15 =W12 =C10 D =E14+F16 =E16-E14 =G16-F16 11 =M16 =MAX(K10,614) G =M14+N16 =M16-M14 =O16-N16 9 |=016 =014 H=Q14+R16 =Q16-Q14 =S16-R16 9 =U14 16

The above project diagram is prepared as per the legend shown in the top-left corner.

EST = Early start time

LST = Late start time

EFT = Early finish time

LFT = Late finish time

SLK = Slack = LST - EST or Slack = LFT - EFT

The EST of an activity = EFT of previous activity

EFT of an activity = EST + Duration

Similarly, LFT & LST are calculated during backward pass.

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