If an airline flies the route between Chicago and Pittsburgh. The mean
number of passengers per flight is 160 with a standard deviation of
20. The aircraft used for the route has 200 seats.

a. What percent of the flights are sold out?

b. The airline must sell 150 seats to break even on this particular
flight. On what percent of the flights does the airline make money?

c. The airline would like to reduce the number of flight attendants on
20 percent of the flights. This will be done on the flights with the
fewest passengers. Below what number of passengers on a flight will
the airline reduce the number of flight attendants?

A study of Furniture Wholesales, Inc. regarding the payment of
invoices revealed that, on the average, an invoice was paid 20 days
after it was received. The standard deviation equaled 5 days.

a. What percent of the invoices are paid within 15 days of receipt?
b. What is the probability of selecting any invoice and finding it was
paid between 18 and 26 days after it was received?
c. The management of Furniture Wholesales wants to encourage their
customers to pay their monthly invoices as soon as possible.
Therefore, it was announced that a 2 percent reduction in price would
be in effect for customers who pay within 7 working days of the
receipt of the invoice. Assuming the payments are normally
distributed, out of 200 customers during July, how many would normally
be eligible for the reduction?

Truck Lines uses the Ford Super 1310 exclusively.
Management made a study of the maintenance costs using a sample. It
revealed that the arithmetic mean number of kilometers traveled per
truck during the year was 60,000. The distances traveled during the
year were normally distributed. The standard deviation of the normally
distributed distances in the sample of Ford 1310s was 2,000
kilometers.

a. What percent of the Ford Super 1310s logged 65,200 kilometers or more?
b. The truck line owns 3,500 Ford Super 1310s. Based on the sample
findings, how many of them traveled 55,000 kilometers or less?
c. How many of the Fords traveled 62,000 kilometers or less during the year?


The price of Corporation stock is normally distributed
throughout the year with a mean of $42.00 per share and a standard
deviation of $2.25 per share.
	
a. What percent of the days is the price over $45.00? If stock is
traded 240 days out of the year, how many days is the price over
$45.00?

b. What percent of the days is the price between $38.00 and $40.00?

c. What is the stock's value on the highest 15 days of the year?
(Again assume that there are 240 trading days in a year.)

In establishing warranties on TV sets the manufacturer wants to set
the limits so that few will need repair at manufacturer expense. On
the other hand, the warranty period must be long enough to make the
purchase attractive to the buyer. For a new TV the mean number of
months until repairs are needed is 36.84 with a standard deviation of
3.34 months. Where should the warranty limits be set so that only 10
percent of the TVs need repairs at the manufacturer's expense?