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Science Forum Index » Statistics - Math Forum » Probability problem
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| Panda |
 Posted: Thu Mar 15, 2007 3:08 pm |
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I have this probability problem
A two-page typed report contains an error on one of the pages. Two proofreaders review the copy. Each has 80% chance of catching the error. What is the probability that the error will be identified if
a. each reads a different page?
b. they each read both pages?
c. the first proofreader randomly selects a page to read, then the second proofreader randomly selects a page unaware of which page the first selected.
I still cannot solve it completely. Does anyone have any idea? |
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| Panda |
| Posted: Fri Mar 16, 2007 4:51 am |
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Here is what I have done.
a. Since each reads a different page, the chance to catch the error is 80%.
b. When they each read both pages, the chance to catch the error is 0.8 + 0.8x0.2 = 0.96.
c. Still not done yet.
That is what I have done. |
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| Guest |
| Posted: Fri Mar 16, 2007 5:47 am |
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In article <17274874.1174007347131.JavaMail.jakarta@nitrogen.mathforum.org>,
Panda <wavifu@yahoo.com> writes:
Quote: I have this probability problem
A two-page typed report contains an error on one of the pages. Two proofreaders review the copy. Each has 80% chance of catching the error. What is the probability that the error will be identified if
a. each reads a different page?
b. they each read both pages?
c. the first proofreader randomly selects a page to read, then the second proofreader randomly selects a page unaware of which page the first selected.
I still cannot solve it completely. Does anyone have any idea?
Don't forget the implicit assumption of independence in b & c.
Is independence reasonable? (If I employed 2 proofreaders reading
the same page, I would want them to tend to make different mistakes!)
-- Ewart Shaw
--
J.E.H.Shaw [Ewart Shaw] strgh@uk.ac.warwick TEL: +44 2476 523069
Department of Statistics, University of Warwick, Coventry CV4 7AL, UK
http://www.warwick.ac.uk/statsdept http://www.ewartshaw.co.uk
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| illywhacker |
| Posted: Fri Mar 16, 2007 9:34 am |
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On Mar 16, 2:08 am, Panda <wav...@yahoo.com> wrote:
Quote: A two-page typed report contains an error on one of the pages. Two proofreaders review the copy. Each has 80% chance of catching the error. What is the probability that the error will be identified if
a. each reads a different page?
b. they each read both pages?
c. the first proofreader randomly selects a page to read, then the second proofreader randomly selects a page unaware of which page the first selected.
I still cannot solve it completely. Does anyone have any idea?
Why don't you tell us how far you have got?
illywhacker; |
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