Q86 of 108 Page 271

The probability that a person is not a swimmer is 0.3. The probability that out of 5 persons 4 are swimmers is

Total number of person , n=5


Total number of swimmers among total person , r=4


Probability of not swimmer , Q=0.3


So, The probability of swimmer , p=1-Q=0.7


We know, probability distribution P(X=r)=nCr (p)r qn-r


P(X) = nCr


P(X) =



Hence, 5C4 (0.7)4 (0.3)

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