Travelers are facing increased costs for both driving and flying to chosen destinations. With rising costs for both modes of transportation, what really weighs on the decision to drive or to fly? To gain a better understanding of the “fly or drive” decision, Runzheimer International reviewed (“The ‘Fly or Drive’ Decision: Runzheimer International Analyzes Costs,” October 21, 2005) costs for trips between Los Angeles to San Francisco, 425 miles one way. Los Angeles to San Francisco round-trip costs $617.90 by car and $407.00 by plane. Cost flexibility is greater with the flying trips because of greater airfare choices.

The driving trip costs, except for the on-road lunches, are pretty much set in place. Assume the standard deviation for the cost of flying trips is approximately

$100.

a. If a flight to San Francisco from Los Angeles was chosen at random, determine the proportion of the time that the cost would be smaller than $507.

Assume the flight costs are bell-shaped.

b. Determine a flight cost that would qualify as the 25th percentile.

c. If nothing can be assumed about the distribution of the flight costs, determine the largest percentile that could be attributed to an airfare of $250.

3-77.With the ups and downs in the economy since 2008, many discount airline fares are available if a customer knows how to obtain the discount. Many travelers complain that they get a different price every time they call. The American Consumer Institute recently priced tickets between Spokane,Washington, and St. Louis, Missouri. The passenger was to fly coach class roundtrip, staying seven days. Calls were made directly to airlines and to travel agents with the following results.

Note that the data reflect round-trip airfare.

$229.00 $345.00 $599.00 $229.00 $429.00 $605.00 $339.00 $339.00 $229.00 $279.00 $344.00 $407.00

a. Compute the mean quoted airfare.

b. Compute the variance and standard deviation in airfares quoted. Treat the data as a sample.