Playing cards

From 32 playing cards containing 8 red cards, we choose 4 cards. What is the probability that just 2 will be red?

Correct answer:

p =  0.2109

Step-by-step explanation:

q=832=14=0.25  C2(4)=(42)=4!2!(42)!=4321=6  p=(42) q2 (1q)42=6 0.252 (10.25)42=271280.2109   Verifying Solution:   C2(8)=(82)=8!2!(82)!=8721=28  C2(24)=(242)=24!2!(242)!=242321=276  C4(32)=(324)=32!4!(324)!=323130294321=35960  p2=(82) (242)(324)=28 27635960=96644950.2149 p2p

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Showing 1 comment:
Math student
I do not understand how you got 4*3 over 2*1 in the probability equation? Shouldn't it have been 4*3*2*1 over 2*1?


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