Question 271306: In a large university, 15% of the students are female. If a random sample of twenty students is selected,
a. what is the probability that the sample contains exactly four female students?
b. what is the probability that the sample will contain no female students?
c. what is the probability that the sample will contain exactly twenty female students?
d. what is the probability that the sample will contain more than nine female students?
e. what is the probability that the sample will contain fewer than five female students?
f. what is the expected number of female students?
Answer by stanbon(75887)   (Show Source):
You can put this solution on YOUR website! In a large university, 15% of the students are female. If a random sample of twenty students is selected,
a. what is the probability that the sample contains exactly four female students?:::20C4(0.15)^4(0.85)^16
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b. what is the probability that the sample will contain no female students?
:::::(0.85)^20
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c. what is the probability that the sample will contain exactly twenty female students?
::::::::::(0.15)^20
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d. what is the probability that the sample will contain more than nine female students?
Using a TI calculator I get: 1 - binomcdf(20,0.15,9)
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e. what is the probability that the sample will contain fewer than five female students?
Using TI calc I get: binomcdf(20,0.15,4)
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f. what is the expected number of female students?
::::: E(x) = np = 20*0.15 = 3
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Cheers,
Stan H.
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