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Probability: OG-11 Ed

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by Uri » Fri Feb 06, 2009 5:26 am
For events A, B and C
P(A) = 0.23
P(B) = 0.40
P(C) = 0.85
Events A and B are mutually exclusive and events B and C are independent.
What can you infer about P(A or C) and P(A and C) from the given information?

This is given as an example in OG 11th ED (bottom of the page 119). But I could not understand their logic. In the last line, it is written, 0.85 =< P(A or C) =< 0.23. Isn't it a mistake?

Could you please explain what we can deduce about P(A or C) and P(A and C) from the given information?
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Re: Probability: OG-11 Ed

by Ian Stewart » Fri Feb 06, 2009 10:20 am
Uri wrote:For events A, B and C
P(A) = 0.23
P(B) = 0.40
P(C) = 0.85
Events A and B are mutually exclusive and events B and C are independent.
What can you infer about P(A or C) and P(A and C) from the given information?

This is given as an example in OG 11th ED (bottom of the page 119). But I could not understand their logic. In the last line, it is written, 0.85 =< P(A or C) =< 0.23. Isn't it a mistake?
Hadn't noticed that before - yes, that's clearly an error in the book. Given the discussion preceding that inequality, I'm pretty sure they mean to say "0.08 <= P(A and C) <= 0.23".
For online GMAT math tutoring, or to buy my higher-level Quant books and problem sets, contact me at ianstewartgmat at gmail.com

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