1. Suppose the salary of assembly line workers has Normal distribution with mean of $20,000, and standard deviation of $3,000.
a) What is the probability that a randomly selected assembly line worker earns more than $22,000?
b) What is the probability that the average salary of 5 assembly line workers is higher than $22,000?
c) What is the probability that the average salary of 15 assembly line workers is higher than $22,000?