1. The U.S. Department of Transportation reported that duringNovember, 83.4% of Southwest
Airlines’ flights, 75.1% of US Airways’ flights, and 70.1% ofJetBlue’s flights arrived on time (USA
Today, January 4, 2007). Assume that this on-time performance isapplicable for flights arriving at
concourse A of the Rochester International Airport, and that 40% ofthe arrivals at concourse Aare
Southwest Airlines flights, 35% are US Airways flights, and 25% areJetBlue flights.
a. An announcement has just been made that Flight 1424 will bearriving at gate in concourse A.
What is the most likely airline for this arrival?
c. What is the probability that Flight 1424 will arrive ontime?
d. Suppose that an announcement is made saying that Flight 1424will be arriving late. What is the
most likely airline for this arrival? What is the least likelyairline?

2. In San Francisco, 30% of workers take public transportationdaily (USA Today, December 21, 2005).
a. In a sample of 10 workers, what is the probability that exactlythree workers take public
transportation daily?
b. In a sample of 10 workers, what is the probability that at leastthree workers take public
transportation daily?

3. Auniversity found that 20% of its students withdraw withoutcompleting the introductory statistics
course. Assume that 20 students registered for the course.
a. Compute the probability that two or fewer will withdraw.
b. Compute the probability that exactly four will withdraw.
c. Compute the probability that more than three willwithdraw.
d. Compute the expected number of withdrawals.

4. Phone calls arrive at the rate of 48 per hour at the reservationdesk for Regional Airways.
a. Compute the probability of receiving three calls in a 5-minuteinterval of time.
b. Compute the probability of receiving exactly 10 calls in 15minutes

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5. More than 50 million guests stay at bed and breakfasts(B&Bs) each year. The website for the Bed
and Breakfast Inns of North America, which averages seven visitorsper minute, enables many
B&Bs to attract guests (Time, September 2001).
a. Compute the probability of no website visitors in a one-minuteperiod.
b. Compute the probability of two or more website visitors in aone-minute period.

6. In a survey conducted by the Gallup Organization, respondentswere asked, “What is your favorite
sport to watch?” Football and basketball ranked number one and twoin terms of preference
(Gallup website, January 3, 2004). Assume that in a group of 10individuals, seven prefer football
and three prefer basketball. A random sample of three of theseindividuals is selected.
a. What is the probability that exactly two prefer football?
b. What is the probability that the majority (either two or three)prefer football?