Question 300281: ``At a college, 6 out of 8 students are sophomores. If 9 students are surveyed, find a) the mean b) the variance c)the standard deviation d) the probability that exactly 3 of the 9 are sophomores e) the probability that at most 3 are sophomores f) the probability that at least 5 are sophomores?
I am very pressed for time I have to hand in my assignment today at 2pm can someone please help me out? i really appreciate it.''.
Answer by stanbon(75887)   (Show Source):
You can put this solution on YOUR website! At a college, 6 out of 8 students are sophomores.
P(soph) = 6/8 = 3/4
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If 9 students are surveyed, find
a) the mean = np = 9(3/4) = 27/4
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b) the variance = npq = (27/4)(1/4) = 27/16
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c)the standard deviation = sqrt(npq) = (3/4)sqrt(3)
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d) the probability that exactly 3 of the 9 are sophomores
binompdf(9,3/4,3) = 0.0087
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e) the probability that at most 3 are sophomores
binomcdf(9,3/4,3) = 0.0100
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f) the probability that at least 5 are sophomores?
1 - binomcdf(9,3/4,4) = 0.9511
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Cheers,
Stan H.
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