Question 75985: Help I am confused
Approximately 25% of the population belongs to a health maintenance organization (HMO). Assume that for a randomly selected group of 20 adults, the number belonging to an HMO has a binomial distribution.
7. The probability of finding exactly 5 in the 20 who belong to an HMO is:
a. 0.2023
b. 0.1567
c. 0.1750
d. 0.2345
The probability of finding at least one in the 20 who belongs to an HMO is:
a. 0.7500
b. 0.8012
c. 0.9056
d. 0.9968
Thank You
Answer by stanbon(75887)   (Show Source):
You can put this solution on YOUR website! Approximately 25% of the population belongs to a health maintenance organization (HMO). Assume that for a randomly selected group of 20 adults, the number belonging to an HMO has a binomial distribution.
7. The probability of finding exactly 5 in the 20 who belong to an HMO is:
a. 0.2023
b. 0.1567
c. 0.1750
d. 0.2345
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n=20 , p=0.25, x=5
P(x=5)=20C5(0.25)^5(0.75)^15 = 0.20
With a T caluculator it is binompdf(20,0.25,5)
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The probability of finding at least one in the 20 who belongs to an HMO is:
a. 0.7500
b. 0.8012
c. 0.9056
d. 0.9968
------
P(at least one) = 1 - P(x=0)
=1 - 20C0(0.25)^0(0.75)^20
=1 - binompdf(20,0,25,0)
=0.9968...
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Cheers,
Stan H.
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