Question 539681
Cars arrive at Kenny's car wash at a rate of 3.4 per half hour. What is the probability that in any given half hour atleast 3 cars arrive in this carwash? 
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Poisson Problem
P(x>=3) = 1 - P(0< x < 3)
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u = 3.4
P(0< x <3) = summation from x = 0 to 3 of [(e^-u*u^x)/x!]
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= [(e^-3.4*3.4^0)/0!] + [(e^-3.4*3.4^1)/1!] + [(e^-3.4*3.4^2)/2!]
+ [(e^-3.4*3.4^3)/3!]
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Using a TI-84 I get P(0<x<3) = poissoncdf(3.4,3) = 0.5584
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So P(x>=3) = 1-0.5584 = 0.4416
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Cheers,
Stan H.
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