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TOPIC: Formulas and Decimals

Formulas and Decimals 2 months 1 week ago #17080

  • Jeanie Burdi
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I'm on Lesson 7.05:Part 2 - Earned Value Analysis
I was following along for Scenario D for EAC. EAC = AC+[(BAC-EV)/(SPI*CPI)]
When I calculated CPI and SPI, I had truncated down to 2 decimal places. I cam up with 1,325K and you had come up with 1,323K.

I reworked my equations and took the decimals out to 5 places instead of 2, and came up with 1,323K.

So, my question is ... how many decimal places is the right number ? I'm sure that on the test there will be 1,325,000 AND 1,323,000 options.

Just wanting to know what is best practice
The graveyard is filled with important men, who could not be spared....
but were... in the end.
Jeanie Burdi

Formulas and Decimals 2 months 1 week ago #17081

  • Cornelius Fichtner
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Jeanie,

Good catch!

You can, however, ignore this line of thinking for the exam. First of all, there are fewer and fewer formula-based questions on the exam, and second, the questions on the exam will be created in such a way that the decimals don't really matter. PMI is not in the business of creating questions that require you to pick "the correct" number of decimals or else you get it wrong.

As a best practice, I recommend: Do NOT truncate your decimals on the exam, unless the question clearly states to 'use 2 decimals only' during the calculation.
Until Next Time,
Cornelius Fichtner, PMP, CSM
President, OSP International LLC

Formulas and Decimals 2 months 1 week ago #17082

  • Jeanie Burdi
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Thank you for the quick answer. I've been googling and every instance of CPI or SPI shows 2 decimals... I'm weird and did an spreadsheet analysis see haphazard paste below. At 4 or 5 decimals, you could round down... but this shows to get closer...6 worked best. Just wasn't sure what test will show.

Goal Number AC EV PV BAC
1,323,000 420,000 400,000 430,000 1,200,000

# Dec AC EV PV BAC CPI SPI EAC
1 420,000 400,000 430,000 1,200,000 1 0.9 1,308,889
2 420,000 400,000 430,000 1,200,000 0.95 0.93 1,325,490
3 420,000 400,000 430,000 1,200,000 0.952 0.93 1,323,587
4 420,000 400,000 430,000 1,200,000 0.9524 0.9302 1,323,014
5 420,000 400,000 430,000 1,200,000 0.95238 0.93023 1,323,003
6 420,000 400,000 430,000 1,200,000 0.952381 0.930233 1,323,000
7 420,000 400,000 430,000 1,200,000 0.952381 0.9302326 1,323,000
8 420,000 400,000 430,000 1,200,000 0.95238095 0.93023256 1,323,000
9 420,000 400,000 430,000 1,200,000 0.952380952 0.930232558 1,323,000
10 420,000 400,000 430,000 1,200,000 0.952380952 0.930232558 1,323,000
The graveyard is filled with important men, who could not be spared....
but were... in the end.
Jeanie Burdi
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