Question

10. Oma Bakery HQ is building a new automated bakery in Taipa. The following table contains the activities that need to be completed to build the bakery and install the facilities.

Activity	Immediate Predecessor	Normal Time	Crash Time	Crash Cost /Week
A	None	9	6	$3,000
B	A	8	5	$3,500
C	A	15	10	$4,000
D	B,C	5	3	$2,000
E	C	10	6	$2,500
F	D,E	2	1	$5,000

a. Draw the network diagram (Activity-on-arrow (AOA) or Activity-on-node (AON)).

b. Which activities have slack, and how many weeks?

c. What is the critical path?

d. How many weeks will Oma Bakery HQ take to complete the project?

e. How many weeks will the project take if Oma Bakery HQ is willing to pay crashing cost as long as it is less than $3,500/week, and show, step by step, how you arrived at your crashing sequence? 10. Oma Bakery HQ is building a new automated bakery in Taipa. The following table contains the activities that need to be completed to build the bakery and install the facilities.

Activity	Immediate Predecessor	Normal Time	Crash Time	Crash Cost /Week
A	None	9	6	$3,000
B	A	8	5	$3,500
C	A	15	10	$4,000
D	B,C	5	3	$2,000
E	C	10	6	$2,500
F	D,E	2	1	$5,000

a. Draw the network diagram (Activity-on-arrow (AOA) or Activity-on-node (AON)).

b. Which activities have slack, and how many weeks?

c. What is the critical path?

d. How many weeks will Oma Bakery HQ take to complete the project?

e. How many weeks will the project take if Oma Bakery HQ is willing to pay crashing cost as long as it is less than $3,500/week, and show, step by step, how you arrived at your crashing sequence?

Answer 1

a. Draw the network diagram (Activity-on-arrow (AOA) or Activity-on-node (AON)).

b. Which activities have slack, and how many weeks?

Activity ‘B’ and ‘D’ is having the slack of 12 weeks and 5 weeks respectively.

Earliest start and the earliest finish are calculated in the forward direction starting from the activity ‘A’ whereas latest start and latest finish is calculated from the backward direction starting from the activity ‘F’.

ES of first activity is zero and LF of last activity is the EF of last activity.

While taking ES, if the activity has two or more predecessor, than the ES will take the value of EF of that activity which has maximum EF.

In this example, ES for activity ‘D’ having ‘B’ and ‘C’ activities as its predecessor, we will chose the EF of ‘C’ for ES of ‘D’ since it is maximum EF among ‘B’ and ‘C’.

While taking LF, if the activity has two or more Successors, than the LF will take the value of LS of that activity which has minimum LS.

In this example, LF for activity ‘C’ having ‘D’ and ‘E’ activities as its successor, we will chose the LS of ‘E’ for LF of ‘C’ since it is minimum LS among ‘D’ and ‘E’.

Activity ‘B’ and ‘D’ is having the slack of 12 weeks and 5 weeks respectively.

c. What is the critical path?

d. How many weeks will Oma Bakery HQ take to complete the project?

Answer: Oma Bakery HQ will take 36 weeks i.e. the critical path duration to complete the project.