Question No. 3

Media matrix collected data showing the most popular Websites when browsing at home and work. The following data show the number of unique visitors (thousands) for the top 10 Web sites when browsing at home.

Web Site	Unique Visitors(1000s)
About.com	5538
Altavista.com	7391
Amazon.com	7986
Angelfire.com	8917
Aol.com	23863
Bluemountainarts.com	6786
Ebay.com	8296
Hotbot.com	5760
Icq.com	5052
Looksmart.com	5984

1. Compute the mean and median, interpret the results.
2. Do you think it would be better to use the mean or the median as the measure of location for this data? Explain
3. Compute and interpret the first and third quartiles, 85^th Percentile, and 6^th Decile.

Question No. 5 (a):

Car rental rates per day for a sample of seven Eastern U.S. cities are as follows (The Wall Street

Journal,January 16, 2004).

City Daily Rate$

Boston 43

Atlanta 35

Miami 34

New York 58

Orlando 30

Pittsburgh 30

Washington, D.C. 36

a) Compute the mean, variance, and standard deviation for the car rental rates.

b) A similar sample of seven Western U.S. cities showed a sample mean car rental

rate of $38 per day. The variance and standard deviation were 12.3 and 3.5, respectively.

Discuss any difference between the car rental rates in Eastern and Western U.S. cities.

Question No. 5 (b):

The following times were recorded by the quarter-mile and mile runners of a university

track team (times are in minutes).

Quarter-Mile Times: 0.92 0.98 1.04 0.90 0.99

Mile Times: 4.52 4.35 4.60 4.70 4.50

After viewing this sample of running times, one of the coaches commented that the quartermilers

turned in the more consistent times. Use the standard deviation and the coefficient

of variation to summarize the variability in the data. Does the use of the coefficient of variation

indicate that the coach's statement should be qualified?