# Thread: Need help w/ "The odds of a man being over 2 meters tall are 0.3...." & 3 other q's

1. ## Need help w/ "The odds of a man being over 2 meters tall are 0.3...." & 3 other q's

I stucked with 4 questions I didnt know how to answer, Ill be glad for an answers. Thank you

1. The odds of a man being over 2 meters tall are 0.3 The odds of a woman being over 2 meters tall are 0.15 If someone is over 2 meters, what are the odds that that person is a man? (the world has an equal number of men and women)?
2. bag with 5 green balls, 5 black balls and 5 red balls. One ball is picked out, and not replaced, and then another ball is picked out. What is the probability of drawing at least 1 black ball?
3. bag with 15 balls, 5 of which are black. What is the expected number of trials for getting a black ball, if we draw a single ball with replacement?
4. Imagine the distribution of clicks to gmail entering account. Which do you think is highest, the mean or the median? or They are Equal (explain Why)

Thank you !

2. Originally Posted by danaavital555@gmail.com
I stucked with 4 questions I didnt know how to answer, Ill be glad for an answers. Thank you

1. The odds of a man being over 2 meters tall are 0.3 The odds of a woman being over 2 meters tall are 0.15 If someone is over 2 meters, what are the odds that that person is a man? (the world has an equal number of men and women)?
2. bag with 5 green balls, 5 black balls and 5 red balls. One ball is picked out, and not replaced, and then another ball is picked out. What is the probability of drawing at least 1 black ball?
3. bag with 15 balls, 5 of which are black. What is the expected number of trials for getting a black ball, if we draw a single ball with replacement?
4. Imagine the distribution of clicks to gmail entering account. Which do you think is highest, the mean or the median? or They are Equal (explain Why)

Thank you !

Please share your work with us ...even if you know it is wrong.

If you are stuck at the beginning tell us and we'll start with the definitions.

http://www.freemathhelp.com/forum/announcement.php?f=33

3. Originally Posted by Subhotosh Khan

Please share your work with us ...even if you know it is wrong.

If you are stuck at the beginning tell us and we'll start with the definitions.

http://www.freemathhelp.com/forum/announcement.php?f=33
unfortunately I don't have final answers

1. I think it should be p( man | tall). my answer is 2/3

2. I did probability tree diagram and I got (2/21 + 5/21 + 5/21)= 0/5714

3. I think it is geometric distribution, the probability to draw black ball is 1/3 so it should be 3 trials

4. I sincerely don't know, I try to think a lot about it and still confuse

4. Originally Posted by Subhotosh Khan

Please share your work with us ...even if you know it is wrong.

If you are stuck at the beginning tell us and we'll start with the definitions.

http://www.freemathhelp.com/forum/announcement.php?f=33
unfrotunely I dont have final answers

1. I think it is conditional probability, so it should be P(man | tall than 2 meters) = 0.3/(0.3+0.15) = 0.3/0.45 = 2/3

2. I did tree diagram and got (2/21 + 5/21 + 5/21) = 0.5714

3. I think it's geometric distribution. the probability to draw black ball is 5/15 = 1/3
so the expected number of trials is 1/P = 1/0.333= 3 trials

4. I try to think about it for hours. I think all the time that means is the highest but I don't know why and I'm confused. I really need help on that question

I also asked my teacher again and she told me that I can think about it as a distribution of sending mail per day for all Gmail accounts.

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