All about flooble | fun stuff | Get a free chatterbox | Free JavaScript | Avatars    
perplexus dot info

Home > Just Math
Is it true? (Posted on 2016-05-02) Difficulty: 1 of 5
If the proportion of blonds among blue-eyed people is greater than among the population as a whole, is it also true that the proportion of blue-eyed people among blonds is greater than among the population as a whole?

Please justify your YES/NO answer. (By A. Savin)

No Solution Yet Submitted by Ady TZIDON    
Rating: 3.0000 (1 votes)

Comments: ( Back to comment list | You must be logged in to post comments.)
Solution Solution by formulas Comment 2 of 2 |
a=blonde, b=blue-eyed

The given statement is the conditional probability
P(a|b)>P(a)

Which by definition is 
P(a and b)/P(b) > P(a)

A bit of manipulation gives
P(a and b)/P(a) > P(b)

Convert back to conditional probability
P(b|a)>P(b)

Which is the answer to the question: YES

  Posted by Jer on 2016-05-02 09:19:38
Please log in:
Login:
Password:
Remember me:
Sign up! | Forgot password


Search:
Search body:
Forums (0)
Newest Problems
Random Problem
FAQ | About This Site
Site Statistics
New Comments (2)
Unsolved Problems
Top Rated Problems
This month's top
Most Commented On

Chatterbox:
Copyright © 2002 - 2017 by Animus Pactum Consulting. All rights reserved. Privacy Information