Question 844321
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Hi,
re reply:  
<u>Assume that the probability distribution of the length of time between sales is exponentially distributed</u>
considering the info given, the Poisson Distribution the best fit
Using TI calculator
Considering a POISSON DISTRIBUTION  P(x; &#956;) =e^(-&#956;)(&#956;^x) / x! 
The syntax is 1 – poissoncdf(mean, largest x-value).
P(x is at least 8 days)  = 1 – poissoncdf(5, 7) = .1334   0r 13.34%