Rudy’s On- Line Office Supplies

When a customer places an order with Rudy’s On-
Line Office Supplies, a computerized accounting information
system (AIS) automatically checks to see if the
customer has exceeded his or her credit limit. Past records
indicate that the probability of customers exceeding their
credit limit is 0.05. Suppose that, on a given day, 20 customers
place orders. Assume that the number of customers
that the AIS detects as having exceeded their credit limit is
distributed as a binomial random variable.
a. What are the mean and standard deviation of the number
of customers exceeding their credit limits?
b. What is the probability that zero customers will exceed
their limits?
c. What is the probability that one customer will exceed his
or her limit?
d. What is the probability that two or more customers will
exceed their limits?I need to know how to perform this on Excel 2010.