A run contains 4 white and 3 red balls. Find the probability distribution of the number of red balls in a random draw of three balls.

Explanation

Three balls are taken out of an urn

Sample space is

=S(RRR,RRW,RWR,WRR,RWW,WRW,WWR,WWW)

Where R represents red ball and W, white ball

Let X= number of red balls.

so possible value of X are 3,2,1,2,1,0 or 0,1,2,3 (no red ball)

P(X=0)=P( No red ball)=P(WWW)

`=frac{4}{7} times frac{3}{6} times frac{2}{5}[``P(R)=frac{3}{7}(P(W)=frac{4}{7})]`

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