1. ) The energy Information Administration reported the following sources of electricity in the United States in 2008:

Source of Electricity	Net Electricity Generation (millions of megawatt-hours)
Coal	1,994.4
Hydroelectric	248.1
Natural Gas	876.9
Nuclear	806.2
Other	184.7

1. Construct a Pareto chart
2. What percentage of power is derived from coal, nuclear, or natural gas?
3. Construct a pie chart
4. For these data, do you prefer using a Pareto chart or the pie chart? Why?
5. (3.63) One of the major measures of the quality of service provided by an organization is the speed with which it responds to customer complaints. A large family-held department store selling furniture and flooring, including carpet, had undergone a major expansion in the past several years. In particular, the flooring department had expanded from 2 installation crews to an installation supervisor, a measurer, and 15 installation crews. The business objective of the company was to reduce the time between when the complaint is received and when it is resolved. During a recent year, the company got 50 complaints concerning carpet installation. The data from the 50 complaints, organized in Furniture represent the number of days, between the receipt of a complaint and the resolution of the complaint.

54	5	35	137	31	27	152	2	123	81	74	27	11
19	126	110	110	29	61	35	94	31	26	5	12	4
165	32	29	28	29	26	25	1	14	13	13	10	5
27	4	52	30	22	36	26	20	23	33	68

1. Compute the mean, median, first quartile, and third quartile.
2. Compute the range, interquartile range, variance, standard deviation, and coefficient of variation.
3. Construct a boxplot. Are the data skewed? If so, how?
4. On the basis of the results of (a) through (c), if you had to tell the president of the company how long a customer should expect to wait to have a complaint resolved, what would you say? Explain.

1. (3.67) A quality characteristic of interest for a tea-bag filling process is the weight of the tea in the individual bags. If the bags are under-filled, two problems arise. First, customers may not be able to brew the tea to be as strong as they wish. Second, the company may be in violation of the truth-in-labeling laws. For this product, the label weight on the package indicates that, on average, there are 5.5 grams of tea in a bag. If the mean amount of tea in a bag exceeds the label weight, the company is giving away product. Getting an exact amount of tea in a bag is problematic because of variation in the temperature and humidity inside the factory, differences in the density of the tea, and the extremely fast filling operation of the machine (approximately 170 bags per minute). The file Teabags, as shown below, contains the weights, in grams, of a sample of 50 tea bags produced in one hour by a single machine:

5.65	5.44	5.42	5.40	5.53	5.34	5.54	5.45	5.52	5.41
5.57	5.40	5.53	5.54	5.55	5.62	5.56	5.46	5.44	5.51
5.47	5.40	5.47	5.61	5.53	5.32	5.67	5.29	5.49	5.55
5.77	5.57	5.42	5.58	5.58	5.50	5.32	5.50	5.53	5.58
5.61	5.45	5.44	5.25	5.56	5.63	5.50	5.57	5.67	5.36

1. Compute the mean, median, first quartile, and third quartile.
2. Compute the range, interquartile range, variance, standard deviation, and coefficient of variation.
3. Interpret the measures of central tendency and variation within the context of this problem. Why should the company producing the tea bags be concerned about the central tendency and variation?
4. Construct a boxplot. Are the data skewed? If so, how?
5. Is the company meeting the requirement set forth on the label that, on average, there are 5.5 grams of tea in a bag? If you were in charge of this process, what changes, if any, would you try to make concerning the distribution of weights I the individual bags? 13.76 You want to develop a model to predict the selling price of homes based on assessed value. A sample of 30 recently sold single-family houses in a small city is selected to study the relationship between selling price (in thousands of dollars) and assessed value (in thousands of dollars). The houses in the city were reassessed at full value one year prior to the study. The results are in House 1. (hint: first determine which are the independent and dependent variables.)
6. Construct a scatter plot and, assuming a linear relationship, use the least-squares method to compute the regression coefficients bo and b1.
7. Interpret the meaning of the y intercept, bo, and the slope, b1, in this problem.
8. Use the prediction line developed in (a) to predict the selling price for a house whose assessed value is $170,000.
9. Determine the coefficient of determination, r2, and interpret its meaning in this problem.
10. Perform a residual analysis on your results and evaluate the regression assumptions.

13.78

The director of graduate studies at a large college of business would like to predict the grade point average (GPA) of students in an MBA program based on Graduate Management Admission Test (GMAC).

1. Construct a scatterplot and, assuming a linear relationship, use the least-squares method to compute the regression coefficients bo and b1.
2. Interpret the meaning of the Y intercept, bo, and the slope, b1, in this problem.
3. Use the prediction line developed in (a) to predict the GPA for a student with a GMAT score of 600.
4. Determine the coefficient of determination,r2, and interpret its meaning in this problem.
5. Perform a residual analysis on your results and evaluate the regression assumptions.