+0  
 
+2
590
2
avatar+474 

A bin has 8 black balls and 7 white balls. 3 of the balls are drawn at random. What is the probability of drawing 2 of one color and 1 of the other color?

 Sep 26, 2017
 #1
avatar+94619 
+1

 

Number of ways to draw  2 black and 1 white  = C( 8,2) * C(7,1)        (1)

 

Number of ways to draw  1 black and 2 white  = C( 8,1) * C(7,2)       (2)

 

Number   of ways to draw  3 balls from 15  =  C( 15,3)     (3)

 

Total Probability  =   [ (1) + (2) ] / (3)  = 

 

[   C( 8,2) * C(7,1)  + C( 8,1) * C(7,2)  ] / [  C( 15,3) ]  = .8  =  80%  

 

 

cool cool cool

 Sep 26, 2017
 #2
avatar
0

its 4

 Sep 26, 2017

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