Question 274633: among com[anies doing highway or brige construction , 80% test employees for substance abuse . A study oinvolves the randam selection of 10 such companies. FIND the probability that exactly 5 of the 10 companies test for substance abuse.(b) find the probability at least half of the companies test for substance abuse.(c) For such groups of 10 companies , find the mean and standard for the number(among) that test for substance abuse.
Answer by stanbon(75887)   (Show Source):
You can put this solution on YOUR website! among companies doing highway or brige construction , 80% test employees for substance abuse.
A study involves the random selection of 10 such companies.
a)FIND the probability that exactly 5 of the 10 companies test for substance abuse
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P(x = 5) = 10C5(0.8)^5*(0.2)^5 = binompdf(10,0.8,5) = 0.0264
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(b) Find the probability at least half of the companies test for substance abuse.
P(5<= x <=10) = 1 - binomcdf(10,0.8,4) = 0.9936
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c) For such groups of 10 companies , find the mean and standard deviation for the number(among 10) that test for substance abuse.
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mean = np = 10*0.8 = 8
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std = sqrt(npq) = sqrt(8*0.2) = sqrt(1.6) = 1.2649
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Cheers,
Stan H.
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