I think back to when I sat for the PMP exam and remember taking the first few minutes to quickly write down the following formulas. It was my cheat sheet. There was enough to think about for the next few hours and worrying if I could remember some key formulas was not one of them. So, here is a bit of advice. If you're preparing[1] to take the PMP exam, **MEMORIZE** these formulas. The exam won't come right out and ask you to identify the correct formula for a variance of an activity. Rather, it will offer a question like: Your current activity was pessimistically estimated at 65 hours and optimistically estimated at 40 hours. What is the variance of the activity? (you can use this formula for both time and cost) You can see how knowing the formula is going to make you or break you on this question.

Do yourself a favor. Make flash cards, get a tattoo, it doesn't matter. Commit these formulas to memory and you'll save yourself some pain and suffering (and a few points on the exam).

### The Formulas

Acronym

Title

Formula

PERT

Program Evaluation and Review Technique

P = Pessimistic Estimate M = Most Likely Estimate O = Optimistic Estimate

Standard Deviation of Activity

Variance of an Activity

Total Float

LS - ES or LF - EF

Communications Channels

[N(N-1)] / 2

CV

Cost Variance

EV - AC

SV

Schedule Variance

EV - PV

CPI

Cost Performance Index

EV / AC

SPI

Schedule Performance Index

EV / PV

EAC

Estimate at Completion

BAC / CPI

AC + ETC

AC + (BAC - EV)

ETC

Estimate to Complete

ETC = EAC - AC

VAC

Variance at Completion

BAC - EAC

CPI

c

Cumulative Cost Performance Index

**Σ**

EV /

**Σ**

AC

TCPI

To-Complete Performance Index