SOLUTION: what is the probability that an employee stays in the same job until retirement is 0.5. There are 1,000 employees that work for the city. What is the probability that 500 or fewer

Question 995243: what is the probability that an employee stays in the same job until retirement is 0.5. There are 1,000 employees that work for the city. What is the probability that 500 or fewer employees stay in their jobs until retirement?
Answer by stanbon(75887) (Show Source): You can put this solution on YOUR website!
what is the probability that an employee stays in the same job until retirement is 0.5. There are 1,000 employees that work for the city. What is the probability that 500 or fewer employees stay in their jobs until retirement?
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Use the normal approximation:
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mean = np = 1000*(1/2) = 500
std = sqrt(npq) = sqrt(500(1/2)) = sqrt(250) = 5sqrt(10)
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P(0<= x <=500) = P(x <= 501)
z(501) = (501-500)/5sqrt(10)) = 1/(5sqrt(10)) = 0.0633
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P(0<= x <= 500) is approximately P(z < 0.0633) = 0.5252
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Cheers,
Stan H.
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