A builder must follow the activity chart below.

Activity Letter	Activity	Predecessor	Time (hrs)
A	Prepare foundation	-	7
B	Door frames	-	2
C	Drains and floor base	-	15
D	Walls	A,B	10
E	Fittings	D	8
F	Roof	D	5
G	Ceiling	E,F	2
H	Doors & Windows	E	8
I	Gutters & Pipes	C,G	2
J	Paint outside	I	3

a) From the activity chart, create a network diagram of the construction process

b) Determine the earliest completion time for all the tasks to be completed

c) Evaluate the reasonableness of the time taken to construct the dwelling.