Question 5 - A-Level Maths

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

Draw the activity network described in the precedence table, using activity on arc. Your activity network must contain only the minimum number of dummies.
(5)
Explain why, in general, dummies may be required in an activity network.