Answer:
0.26503
Step-by-step explanation:
Assume that everyone that enters the store is with equal probability for both sexes
Let X be the total number of people that enter the store
Let Y be the number of men that enters the store
Let Z be the number of women that enters the store
X = 10
Y = Z = (1/2)10
Y = Z = 10/2
Y = Z = 5
Since both men and women have the same probability, λ = 5 for each occurrence
Using Poisson distribution we can find the probability using the formula
Pr(Y) = (λ^Y)(e^- λ) /Y!
Pr(Y≤3) = Pr(Y=0) +Pr(Y=1) + Pr(Y=2) + Pr(Y=3)
Pr(Y=0) = ( 5^0)(e^-(5)) /0!
= 0.006738
Pr(Y=1) = ( 5^1)(e^-(5)) /1!
= 5*0.006738 / 1
= 0.03369
Pr(Y=2) = ( 5^2)(e^-(5)) /2!
= 25*0.006738 / 2
= 0.084225
Pr(Y=3) = ( 5^3)(e^-(5)) /3!
= 125*0.006738 /6
= 0.140375
Pr(Y≤3) = 0.006738 + 0.03369 + 0.084225 + 0.140375
= 0.26503