Q1. What are the expected value and standard deviation of X, where X is the number of customers she meets in a week?
Q2. What is the probability that she meets exactly five customers in a week?
更新1:
謝謝你的提醒,自由自在。 Mary is a clerk. The following is the probability distribution function of the number of customers she meets in a day, Z. x=0,1,2,3,4 P(Z=x)=0,3c,2c,c,c