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
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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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