Question 4 - A-Level Maths

Activity	Immediately preceding activities
A	-
B	-
C	A, B
D	A, B
E	B
F	C, D, E
G	F
H	B
I	F
J	F
K	G
L	G, H, I, J
M	G, I

Draw the activity network described in the precedence table, using activity on arc and the minimum number of dummies.
Given that
- the activity network contains only one critical path
- activity E is on this critical path
  state
  1. which activities could never be critical,
  2. which activities must be critical.