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jainvineet
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# of ways to pick 4 people from 10 = 10C4 = 10!/4!6! = 210 ways

# of ways to pick 2 women = 4C2 = 6
# of ways to pick 2 men = 6C2 = 15
Total number of ways that half of committe is women = 15*6 = 90

P = 90/210 = 3/7
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Antmavel
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jainvineet
Antmavel
(2C6*2C4)/(4C10) = 3/7

Please explain why cant we have it like


6/10 * 5/9 * 4/8 * 3/7


probability of a man out of 10 and then a man out of 9 and so on.

This is the key thing I am not able to understand.


I am not a specialist but I think that the reason is because when you organize your calculation like you've suggested before, you're giving a precise order.
For example : 6/10*5/9*4/8*3/7 is ok, but don't you think that 4/10*6/9*3/8*5/7 is also correct ? of course the result will be the same but it's another way to get also half of the people to be women. When you use combinations you calculate all the possible ways to get a result.

Moreover, if you take some extra time you will see that there are 4W and 6M, we need 4 people, half men and half women. If there were 5W and 5M the probability would be 50% but now there are 4W and 6M so the probability to pick 2W and 2M should be a little lower. But 1/14 is not a realistic figure, it's too low :wink:
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jainvineet
Antmavel
(2C6*2C4)/(4C10) = 3/7

Please explain why cant we have it like


6/10 * 5/9 * 4/8 * 3/7


probability of a man out of 10 and then a man out of 9 and so on.

This is the key thing I am not able to understand.


In your approach you would count ABCD as a different outcome from DCBA, while they are actually the same group of four people, just picked in different orders. If you do this then you need to divide your result by P(4,4).



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