ROM (rough order of magnitude)Question

Submitted by thiru26@gmail.com on Mon, 09/14/2015 - 01:35

You are working for FALCON highway construction agency as a project cost estimator. The agency started a highway construction project which is in it's planning phase. The rough order of magnitude (ROM) cost estimate for the project is expected to be between 3 and 5 million dollars in the planning phase with a ROM of -25% to +25%. What will be the ROM estimate in the execution phase if it changes to -10% to +10%?

  1. Between 3.1 and 4.1 million dollars

  2. Between 3.6 and 4.4 million dollars

  3. Between 3.9 and 4.1 million dollars

  4. Between 3.4 and 4.4 million dollars

 

Below is the answer, but need to understand how the calculations was made to come up with below answer.

18th Question from PMP Lite Mock Exam 18 Practice Questions—Answer Key and Explanations

 

B - Since the Rough Order ofMagnitude (ROM) in the planning phase is -25% to +25%, the estimated mean value is 4 million dollars. If the estimates narrows down to -10% to +10% it becomes 3.6 to 4.4 million dollars. [PMBOK 5th edition, Page 201] [Project Cost Management]

 

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thiru26@gmail.com

Tue, 09/15/2015 - 20:28

Experts and Admins

Appreciate if some one can through light on this question.

brian mahon

Thu, 09/17/2015 - 05:25

If you need a process - Here's one.

Your looking for the mean value and your being asked to adjust it by 10%.

We know that 1.25 the mean is 5 therefor the mean is 5/1.25 = 4, Same deal with 3, 3/0.75 = 4.

So 4 +/- 10% is 3.6 to 4.4.

thiru26@gmail.com

Fri, 09/18/2015 - 02:05

Thanks for the explanations.

Got it.