Suppose a researcher goes to a small college of 200 faculty, 12 of which have blood type O-negative. She obtains a simple random sample of the faculty. Let the random variable X represent the number of faculty in the sample of size that have blood type O-negative.
a. What is the probability that 3 of the faculty have blood type O-negative?
b. What is the probability that at least one of the faculty has blood type O-negative?
Let "X=" the number of faculty who have blood type O-negative: "X\\sim Bin (n, p)."
Given "p=12\/200=0.06, q=1-p=0.94, n=20."
a.
"=0.08600666617"
b.
"=1-\\dbinom{20}{0}(0.06)^{0}(0.94)^{20-0}"
"=0.70989375886"
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