# Statistics question
**URL:** https://boards.straightdope.com/t/statistics-question/453327
**Category:** Factual Questions
**Created:** [June 18, 2008, 12:02pm UTC](https://boards.straightdope.com/t/statistics-question/453327 "2008-06-18T12:02:13Z")
**Posts on this page:** 7
**Page:** 1
### Author:  [@One\_And\_Only\_Wanderers](https://boards.straightdope.com/u/One_And_Only_Wanderers)
#### Post date: [June 18, 2008, 12:02pm UTC](https://boards.straightdope.com/t/statistics-question/453327/1 "2008-06-18T12:02:13Z")
Have I approached this question correctly?
50 people in a call centre. Th chance of a person being off is 0.02
what is the probability of no more than 2 people being off
3 outcomes match this, everyone in, 1 off & 2 off
everyone in
0.98 to the power 50 = .3642
1 off
0.98 to the power of 49 \* 0.2 \* 50 = .3716 (the 50 comes from 50 C 1)
2 off
0.98 to the power of 48 \* 0.2 to the power of 2 \* 1225 = .1858 (the 1225 comes from 50 C 2)
so the answer to the q would be .3642 + .3716 + .1858 = 0.9216
I _think_ I have the right answer but it’s been a while since I did my Mathematics A Level.
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### Author:  [@Snarky\_Kong](https://boards.straightdope.com/u/Snarky_Kong)
#### Post date: [June 18, 2008, 1:09pm UTC](https://boards.straightdope.com/t/statistics-question/453327/2 "2008-06-18T13:09:19Z")
You should be using 0.02, not 0.2.
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### Author:  [@One\_And\_Only\_Wanderers](https://boards.straightdope.com/u/One_And_Only_Wanderers)
#### Post date: [June 18, 2008, 1:13pm UTC](https://boards.straightdope.com/t/statistics-question/453327/3 "2008-06-18T13:13:44Z")
[QUOTE=Snarky\_Kong]
You should be using 0.02, not 0.2.
[/QUOTE]
Doh! Thats a typo, the answers given did use .02
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### Author:  [@hawthorne](https://boards.straightdope.com/u/hawthorne)
#### Post date: [June 18, 2008, 1:32pm UTC](https://boards.straightdope.com/t/statistics-question/453327/4 "2008-06-18T13:32:47Z")
You are assuming that the probabilities are independent. This is a _very_ strong assumption and is highly unlikely to be true.
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### Author:  [@One\_And\_Only\_Wanderers](https://boards.straightdope.com/u/One_And_Only_Wanderers)
#### Post date: [June 18, 2008, 1:40pm UTC](https://boards.straightdope.com/t/statistics-question/453327/5 "2008-06-18T13:40:47Z")
[QUOTE=hawthorne]
You are assuming that the probabilities are independent. This is a _very_ strong assumption and is highly unlikely to be true.
[/QUOTE]
The question statd the chance of anyone being off was 1 in 50. Nothing was said about subsequent absentees chancs bing dependant on the prior absentees, so yes I have calculatd assuming independent probabilities of absence
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### Author:  [@ultrafilter](https://boards.straightdope.com/u/ultrafilter)
#### Post date: [June 18, 2008, 1:51pm UTC](https://boards.straightdope.com/t/statistics-question/453327/6 "2008-06-18T13:51:11Z")
The calculations are correct assuming independence of absentee employees. Whether that’s a reasonable assumption is another question.
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### Author:  [@Thudlow\_Boink](https://boards.straightdope.com/u/Thudlow_Boink)
#### Post date: [June 18, 2008, 3:36pm UTC](https://boards.straightdope.com/t/statistics-question/453327/7 "2008-06-18T15:36:48Z")
[QUOTE=ultrafilter]
The calculations are correct assuming independence of absentee employees. Whether that’s a reasonable assumption is another question.
[/QUOTE]
If this is an “artificial” question (like on a test or homework), it almost certainly is, since otherwise there’s not enough information given. In the real world, though…