Take the 2-minute tour ×
Mathematics Stack Exchange is a question and answer site for people studying math at any level and professionals in related fields. It's 100% free, no registration required.

I am currently working on a problem from my statistics class. It is as follows:

enter image description here

The only one I had difficulty quantifying with words was problem f). How would I do that?

Also, I had originally assumed the three events were disjoint; but, by looking at the question again, I found that they aren't, because of the last piece of information given--the intersection of all of the events. I am having a hard time understanding how they are not disjoint. How can these particular three events have something in common? It just seems odd.

share|improve this question
add comment

1 Answer 1

up vote 2 down vote accepted

How can these particular three events have something in common?

If you assume they are disjoint, that means that if the consulting firm gets Project 1 they can't possibly also get Project 2 or Project 3. That's a strong assumption! Why should getting Project 1 keep them from also getting a contract for Project 2?

As for the one you were having trouble interpreting, we have $$(A_1' \cap A_2') \cup A_3.$$ $A_1'$ means they did not get Project 1, similarly for $A_2'$. So this statement says "They failed to get both Project 1 and Project 2, or they got Project 3." And remember that the "or" is not exclusive.

share|improve this answer
    
Well, how do we account for the fact, in your explanation, that $A_3$ contains portions of $A_1$ and $A_2$? –  Mack Jan 26 '13 at 18:47
1  
@EMACK using the laws of probability, including in particular the inclusion/exclusion principle –  Jonathan Christensen Jan 26 '13 at 18:48
1  
Oh, yes, I see clearly, now. Thank you! –  Mack Jan 26 '13 at 18:50
add comment

Your Answer

 
discard

By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.