Solution: average = in =5? (This is the characteristic of Poisson distribution)

Poisson distribution formula: P(X=K)= (into k? )* (e (-in)) /k！ (Editing is not easy, please refer to the textbook if you don't understand)

p(X = K & gt； 4)= 1-p(X = 4)-p(X = 3)-p(X = 2)-p(X = 1)-p(X = 0)

=0.5595

Note that there are more than 4 people, and my calculation does not include 4 people.

Especially it is more convenient to calculate with EXCEL: p (x = k > 4)= = 1- poisson (4,5, 1)=0.5595.