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NDA Math Probability

Question : 81 of 100

Marks: +1, -0

Solution:

We know that the mean and variance of a binomial distribution with number of trials as ‘n’ and the probability of success as ‘p’ are

Mean = np

Variance = np(1-p)

Therefore applying the given conditions yields us

np=2

np(1-p)=1

2(1-p)=1

1-p=\frac{1}{2}

p=\frac{1}{2}

Therefore the number of trials will be 4

P(X=0)

=\binom{4}{0}(1-P)^4

=\frac{1}{2^4}

=\frac{1}{16}

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