Question 299896: The probability that an employee at the company is over 40 years old is 0.6. If 18 employees are asked heir age, find the probability that a)exactly 3 are over 40 years old, b) at least 9 are over 40 years old, c)fewer than 4 are over 40, find the d) mean, e) variance, f) standard deviation.
I am pressed for time my professor doesn't really speak understandable english and I dont want to fail his class I understand mostly on my own but a few of my problems I need assistance with pls help if you can.
Answer by stanbon(75887)   (Show Source):
You can put this solution on YOUR website! The probability that an employee at the company is over 40 years old is 0.6. If 18 employees are asked heir age, find the probability that
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You need some understanding of technology or of a binomial table
to get answers for a,b, and c:
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a)exactly 3 are over 40 years old = P(x=3) = 18C3(0.6)^3*(0.4)^15
= 0.0001893..
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b) at least 9 are over 40 years old
= 1-P(0<= x <=8) = 1-binomcdf(18,0.6,8) = 0.8653
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c)fewer than 4 are over 40,
binomcdf(18,0.6,3) = 0.0002148
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find the
d) mean = np = 18*0.6 = 10.8
e) variance = npq = 10.8*0.4 = 4.32
f) standard deviation = sqrt(4.32) = 2.0785
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Cheers,
Stan H.
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