Note for Ch5_data: Go through hyperlink to data file Stat_01_data. Save the file as "html" to your floppy disc. Open the file in Excel 97. Save the file as an Excel 97 file. Copy the data for each problem into Minitab and calculate the answers.

1. The owner of a hardware store that sells electric wire by the meter is considering selling the wire in precut lengths to save on labor costs (no one would be required o cut wire to custom lengths). A sample of wire sold over the course of one week was recorded and stored in the Stat_01_data file.

a) Compute the mean, median and mode

b) For each measure of central location calculated in part a), discuss the weakness in providing useful information to the owner.

2. The amount of time (in seconds) to perform a spot weld on a car under production was recorded for 50 workers. These times are stored in Stat_01_data file.

a) Compute the mean, media and mode o these data

b) Discuss what information you have discovered from the statistics computed in part a).

3. The annual total rates of return on common stock and long-term government bonds, for each of 30 are in stored in Stat_01_data file. To understand the meaning of these returns, consider the 15.56% return that was realized on common stock in 1963. This means that $100 invested in common stocks at the beginning of 1963 would have yielded a profit of $15.56 over the year, leaving a total of $115.56 at year's end.

a) Find the mean, median, range, and standard deviation of this sample of common-stock returns.

b) Repeat part a) for government bonds

c) Which type of investment (common stock or bonds) appears to have the higher level of risk?

d) Which type has the higher average return?

e) Compute the mean stock return for each of the six 5-year periods

f) Compute the mean and standard deviation of the six mean returns in part e). Compare these values with the mean and standard deviation calculated in part a), and explain any differences observed.

4. The Number of customers entering a bank during each hour of operation (10:00 am - 3:00 pm) for each of the last 100 days was recorded and stored in Stat_01_data file.

a) For each hour of operation, determine the mean and standard deviation

b) Briefly describe what the statistics in part a) tell you.

5. A bookstore has determined that weekly sales of Newsweek have an approximately mound-shaped distribution, with a mean of 85 and a standard deviation of 6.

a) For what percentage of the time can we expect weekly sales to fall in the intervals x-bar +/- s and x-bar +/- 3s?

b) For what percentage of the time can we expect weekly sales to have a value that is more than 2 standard deviations from the mean?

c) If the bookstore stocks 97 copies of Newsweek each week, for what percentage of weeks will there be an insufficient number of copies to meet the demand? (Hint: a Mound shaped distribution is symmetrical)

6. Last year, the rates of return on the common stocks in a large portfolio had an approximately mound-shaped distribution, with a mean of 20% and a standard deviation of 10%.

a) What proportion of the stocks had a return of between 10% and 40%?

b) What proportion of the stocks had a return of between -10% and 50%?

c) What proportion of the stocks had a return that was either less than 10% or more than 30%

d) What proportion of the stocks had a positive return? (Hint: a Mound shaped distribution is symmetrical)

7. The data for 50 observations of variables X and Y are stored in Stat_01_data file.

a) Determine the covariance between X and Y

b) Determine the correlation coefficient between X and Y

c) Interpret the meaning of the covariance and correlation coefficient

8. The annual percentage rates of return on common stock and annual inflation rates (as measured by percentage changes in the Consumer Price Index) from 1960 through 1994 are stored in Stat_01_data file.

a) Compute cov(X,Y) and r

b) What do these statistics tell you about the relationship between common-stock returns and inflation over this long period?

c) Does it appear that common stocks provide a good hedge against inflation? Why?

9. Slow play on golf courses frustrates most golfers and costs owners thousands of dollars annually. To find ways to speed up the game, the manager of one course undertook a study. The amount of time to complete a round of golf taken by samples of four different groups of golf foursomes was observed and recorded in the Stat_01_data file using the following format:

Column 1: time taken by four men without electric carts

Column 2: time taken by four men with electric carts

Column 3: time take by four women without electric carts

Column 4; time take by four women with electric carts

For each sample, perform the following analysis:

a) Draw the histogram (I require 4 graphs)

b) Calculate the mean (I require 4 means)

c) Calculate the median (I require 4 median)

d) Calculate the standard deviation (I require 4 standard deviation s)

e) Interpret your findings and describe the similarities and differences among the four groups.

10. A growing concern for educators in the United States is the number of teenagers who have part-time jobs while they attend high school. It is generally believed that the amount of time teenagers spend working is deducted from the amount of time devoted to schoolwork. To investigate this problem, a school guidance counselor took a random sample of 200 15-year-old high school students and asked how many hours per week each worked at a part-time job. The results were recorded and stored in Stat_01_data file.