Activity on node help

[brianbrown]

Hi, I have just started a basic construction qualification and im starting to learn the basics of project scheduling. I have been given an assignment to create a Gantt chart, activity on arrow diagram and find the CPA aswell as noting the earliest and latest start times.

I have been given the following information and have typed this into ms project and created a Gantt chart. You can see from the chart that tasks D,E and G have no proceeding activities and the Gantt chart shows that the latest finishing time for these 3 task is the last week of the project (week 49) this bit I understand but its when I get to the arrow on node diagram that I get confused. You can see in pic 1 I have 3 dummy arrow which are the 3 task with no preceding activities, according to the gantt chart these can finish on week 49 so ive typed week 49 ( nodes 5,6 and 8) is this correct???? The other way ive done (pic2) is to change the finish time to the nearest node, however on nodes 6 and 8 ive had to use a node which is a few in advance so there isn’t negative slack. However doing it this way the 3 task’s don’t have a latest finish time of 49 weeks like the Gantt chart shows?????

I hope this makes sense. Im sorry if it doesn’t, but im very new to this.

Could some one please explain if im doing it right and if so, which diagram is correct regarding the slack.
Brian

Activity Description Duration (Wk’s) Preceding tasks
A Outline Design 4 None
B Cost Estimates 2 A
C Client Review 2 B
D Planning Application 8 C
E Site Investigation 2 C
F Detailed Plans 4 C
G Building Regulations 6 F
H Tendering 4 F
I Client Approval 1 H
J Construction 30 I
K Fitting Out 1 J
L Client Hand Over 1 K