Random Sample

In a large university, 15% of the students are female if a random sample of twenty students is selected.

What is the probability that sample contains exactly four female students?

What is the expected number of female students?

Does this mean use the Binomial Probability Function?

Quote:

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Originally Posted by hrunup

In a large university, 15% of the students are female if a random sample of twenty students is selected.

What is the probability that sample contains exactly four female students?

What is the expected number of female students?

Does this mean use the Binomial Probability Function?

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Yes.

X is the random variable number of females in sample.

X ~ Binomial(n = 20, p = 0.15)

Find Pr(X = 4) and E(X).