Q. calculation estimate
Submitted by y0zh on Thu, 05/09/2013 - 19:17
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%?
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Between 3.1 and 4.1 million dollars
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Between 3.6 and 4.4 million dollars
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Between 3.9 and 4.1 million dollars
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Between 3.4 and 4.4 million dollars
1 million=0.25
x million=0.1
then x million=0.1/0.25=0.4
and we still use the mean of 4 millon -+ 0.4? am I correct with calculations?
Forums:
crushPMP
Thu, 05/09/2013 - 19:21
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1.25 * x = 5 x = 5/1.25 =
1.25 * x = 5
x = 5/1.25 = 4
Now, -10% to +10% of 4million is
3.6 to 4.4
Ans B
y0zh
Thu, 05/09/2013 - 19:22
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what is 1.25?
what is 1.25?
crushPMP
Thu, 05/09/2013 - 19:23
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25%
25%
y0zh
Thu, 05/09/2013 - 19:26
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25%=0.25
25%=0.25
-+25% will be 1.25 and 0.75, in this case why you've chosen 1.25 and not 0.75
crushPMP
Thu, 05/09/2013 - 19:30
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I could have done it that way
I could have done it that way also. Either way works (see below)
0.75 * x = 3
x = 3/0.75 = 4
Now, -10% to +10% of 4million is
3.6 to 4.4
Ans B
crushPMP
Thu, 05/09/2013 - 19:33
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Being a white guy, I can't do
Being a white guy, I can't do any better explaination that this.
Hope that helps.
y0zh
Thu, 05/09/2013 - 19:35
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I was calculated 4 million
I was calculated 4 million as average (3+5)/ total deviation 50%=4 million. Looks like both methods work
crushPMP
Thu, 05/09/2013 - 19:39
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Your method luckily worked as
Your method luckily worked as it was -25% on the left side and +25% on the right side of the bell curve, which means a range of 50%. i.e. 1/2. So your avergaging worked.
bkthakkar
Fri, 05/10/2013 - 01:00
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Good explanation
Good explanation