QUICK MATH QUESTION - HELP

Kenji4861

Banned
Jan 28, 2001
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Say there is a group of people

there is a 10% chance of the person being a girl

there is a 90% chance of the person being a guy

What is the probability that if 10 people were picked at random, 3 are girls?


THANKS!
 

wabbiter

Member
Nov 15, 1999
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what is the chance you will pick one girl. 10%, or 0.1
2 girls? 10% for the first girl, 10% for the second girl (this is assuming that you are putting the girl back into the group after you pick her and are thus not changing your percentage)

so what is your chances of picking 3 girls:

10% ^3

and your chances of picking 7 guys:

90% ^ 7

multipled together:

10%^3 = .001

90%^7 = 0.4782969

10%^3 * 90%^7 = 0.004782969

I think this is right
 

Viper GTS

Lifer
Oct 13, 1999
38,107
433
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Can you safely assume that each selection does not alter the demographics of the room?

For example, let's say initially you had 10 girls & 90 guys.

If you drew a guy initially, your odds of drawing a guy on your second try are 89/99. If you draw another guy, the odds become 88/98, etc.

Viper GTS