PERT vs CPM vs BUDGET

Looks like CPM is close to Budgeting, doesnt it?

Activity	Critical Path Method Budget - Deterministic method							Days Most likely (M)	Actual work Completed	Project cost (Days * Costs)	Stage of completion %
A	Purchasing material and warehousing at site							7	✓	3,00,000	20%
B	Bulldozing to prepare constructing foundation							3	✓	50,000	3%
C	Laying foundation							15	✓	100000	7%
D	Foundation watering time							15	✓	20000	1%
E	1st tower layer							10	✓	300000	20%
F	2nd tower layer							10	✓	300000	20%
G	Final tower layer and installing satellite equipment							12	✓	400000	27%
	Total Estimations							72		14,70,000	100%
	Project evaluation and Review Technique (PERT) - Probability model						Optimistic (O)	Most likely (M)	Pessimistic (P)	PERT Estimates = (O+4M+P)/6	Sigma (P-O/6)	Pert variance
A	Purchasing material and warehousing at site						5	7	11	24	1.0	1
B	Bulldozing to prepare constructing foundation						2	3	7	4	0.8	0.7
C	Laying foundation						10	15	25	17	2.5	6.3
D	Foundation watering time						10	15	30	21	3.3	11.1
E	1st tower layer						7	10	20	12	2.2	4.7
F	2nd tower layer						7	10	20	12	2.2	4.7
G	Final tower layer and installing satellite equipment						9	12	20	13	1.8	3.4
	Total									101	14	32
	STANDARD DEVIATION=			3.7	days
	Probability of completing project in 102 days= 102-101/SD					0.268866
	Using Z- Table, 0.27= 99.6% probability that work can be completed in 102 days

	Probability of completing the work in 72 days= 72-101/SD					-7.79713
	Using Z- Table, -7.79713 = 0.832
So,	1-0.832=	0.168	or 16.80% probability that work will be completed in 72 days

Sorry to members for the above mishap, my assumptions are

First, budget can be prepared-> CPM days can be calculated using the best combination of activities -> PERT can use the most likely estimate from CPM.

In this example, a cell phone company can monitor its own tower erections and this will reduce their learning curve impact on expenses and time scales. That info can be used by CPM deterministic modelling.

When it is a start-up, people can go by research and use PERT. This ways one can compare the actual from budgeted. These approximations can be included from budget and do not worry about the number of days increasing because, I heard from one stats guy that Linear programming and Extrapolation has the tendency to inflate the result due to averaging.

Similarly, cell company can do repeated PERT analysis as a hypothesis for every tower erection and can redefine a formula as well or define a margin to be subtracted from the result to give closer approximate results is what I think.

Note: I have attached screenshots for your convenience