Solution-Compute the sample variance

Compute the sample variance

Assignment Help Applied Statistics

Reference no: EM13728963

Question 1:

a. What is the average miles per gallon for city driving?

b. On average, how much higher is the miles per gallon for highway driving as compared to city driving?

FUEL ECONOMY INFORMATION FOR 10 AUTOMOBILES

City Highway
Car Size Cylinders MPG MPG Fuel
Audi A8	Large	12	13	19	Premium
BMW 328Xi	Compact	6	17	25	Premium
Cadillac CTS	Midsize	6	16	25	Regular
Chrysler 300	Large	8	13	18	Premium
Ford Focus	Compact	4	24	33	Regular
Hyundai Elantra	Midsize	4	25	33	Regular
Jeep Grand Cherokee	Midsize	6	17	26	Diesel
Pontiac G6	Compact	6	15	22	Regular
Toyota Camty	Midsize	4	21	31	Regular
Volkswagen Jetta	Compact	5	21	29	Regular

Question 2:

Business Week North American subscriber study collected data from a sample of 2861 subscribers. Fifty-nine percent of the respondents indicated an annual income of $75,000 or more, and 50% reported having an American Express credit card.

a. What is the population of interest in this study?

b. Is annual income a categorical or quantitative variable?

c. Is ownership of an American Express card a categorical or quantitative variable?

d. Does this study involve cross-sectional or time series data?

e. Describe any statistical inferences Business Week might make on the basis of the survey.

Question 3:

The following crosstabulation shows household income by educational level of the head of household (Statistical Abstract of the United States: 2008).

Educational Level	Under 25	Household Income ($1000s) 25.0- 50.0- 75.0- 49.9 74.9 99.9			100 or more	Total
Not H.S. graduate	4207	3459	1389	539	367	9961
H.S. graduate	4917	6850	5027	2637	2668	22099
Some college	2807	5258	4678	3250	4074	20067
Bachelor's degree	885	2094	2848	2581	5379	13787
Beyond bach. deg.	290	829	1274	1241	4188	7822
Total	13106	18490	15216	10248	16676	73736

a. Compute the row percentages and identify the percent frequency distributions of income for households in which the head is a high school graduate and in which the head holds a bachelor's degree.

b. What percentage of households headed by high school graduates earn $75,000 or more? What percentage of households headed by bachelor's degree recipients earn $75,000 or more?

c. Construct percent frequency histograms of income for households headed by persons with a high school degree and for those headed by persons with a bachelor's degree. Is any relationship evident between household income and educational level?

Question 4:

Contains a portion of the data in the file named Fortune. Data on stockholders' equity, market value, and profits for a sample of 50 Fortune 500 companies are shown.

a. Prepare a crosstabulation for the variables Stockholders' Equity and Profit. Use classes of 0 -200, 200-400, . , 1000-1200 for Profit, and classes of 0-1200, 1200-2400,

4800-6000 for Stockholders' Equity.

b. Compute the row percentages for your crosstabulation in part (a).

c. What relationship, if any, do you notice between Profit and Stockholders' Equity?

Question 5:

The Los Angeles Times regularly reports the air quality index for various areas of South-em California. A sample of air quality index values for Pomona provided the following data: 28, 42, 58, 48, 45, 55, 60, 49, and 50.

a. Compute the range and interquartile range.

b. Compute the sample variance and sample standard deviation.

c. A sample of air quality index readings for Anaheim provided a sample mean of 48.5, a sample variance of 136, and a sample standard deviation of 11.66.

What compari¬sons can you make between the air quality in Pomona and that in Anaheim on the basis of these descriptive statistics?

Question 6:

Five observations taken for two variables follow.

x.	4	6	11	3	16
y_i	50	50	40	60	30

a. Develop a scatter diagram with x on the horizontal axis.
b. What does the scatter diagram developed in part (a) indicate about the relationship between the two variables?
c. Compute and interpret the sample covariance.
d. Compute and interpret the sample correlation coefficient.

Question 7:

Consider the sample data in the following frequency distribution.

Class	Midpoint	Frequency
3-7	5	4
8-12	10	7
13-17	15	9
18-22	20	5

a. Compute the sample mean.

b. Compute the sample variance and sample standard deviation.

Reference no: EM13728963

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Compute the sample variance

Reference no: EM13728963

Reference no: EM13728963

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