Answer to Question #298323 in Statistics and Probability for gwapo

Question

Suppose an average of  5 cars arrive at the parking lot every  15 minutes. What is the probability that exactly  4 cars will arrive in the next  15 minutes?

Answer 1

we define p ( x=4 ) as the probability of exactly four cars arriving

Assuming that the random variable x has a poison distribution with mean = 5 and x = 4, we have

p ( x=4 ) = ( ( e^-5) * ( 5⁴) ) / ( 4*3*2*1) which yields 0.175467370 which is the required probability.