Q11 of 77 Page 32

Five defective mangoes are accidentally mixed with 15 goods ones. Four mangoes are drawn at random from this lot. Find the probability distribution of the number of defective mangoes.

X represents the number of defective mangoes drawn.


∴ X can take values 0,1,2 or 3


∵ there are total 20mangoes (15good+5defective) mangoes


n(S) = total possible ways of selecting 5 mangoes =


P(X = 0) = P(selecting no defective mango) =


P(X = 1) = P(selecting 1 defective mango and 3 good mangoes)


=


P(X = 2) = P(selecting 2 defective mangoes and 2 good mangoes)


=


P(X = 3) = P(selecting 3 defective mangoes and 1 good mango)


=


P(X = 4) = P(selecting 4 defective mangoes and no good mango)


=


Now we have pi and xi.


Following table represents the probability distribution of X :



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