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| m102650 | The following data represent tonnes of wheat harvested each year (1894-1925) from Plot 19 at the Rothamsted Agricultural Experiment Stations, England.
(a) Multiply each data value by 100 to "clear" the decimals.
(b) Use the standard procedures of this section to make a frequency table and histogram with your whole-number data Use six classes.
(c) Divide class limits, class boundaries, and class midpoints by 100 to get back to your original data values. |
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| m102651 | The following data represent trunk circumferences (in mm) for a random sample of 60 4-year-old apple trees at East Mailing Agriculture Research Station in England (Reference: S. C. Pearce, University of Kent at Canterbury). Note: These data are also available for download at the Companion sites for this text.
(a) Make a stem and leaf display of the tree circumference data.
(b) Make a frequency table with seven classes showing class limits, class boundaries, midpoints, frequencies, and relative frequencies.
(c) Draw a histogram.
(d) Draw a relative-frequency histogram.
(e) Identify the shape of the distribution.
(f) Draw an ogive.
(g) How are the low frequencies shown in the histogram reflected in the steepness of the lines in the ogive? |
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| m102652 | The following data show the number of rental cars in service for three rental car companies: Hertz, Avis, and Dollar, over a four-year period.
a. Construct a time series graph for the years 1 to 4 showing the number of rental cars in service for each company. Show the time series for all three companies on the same graph.
b. Comment on who appears to be the market share leader and how the market shares are changing over time.
c. Construct a bar chart showing rental |
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| m102653 | The following data show the percentage of 17- to 24-year-olds who are attending college in several metropolitan statistical areas in four geographic regions of the United States (U.S.Census Bureau website, April 2015).
Use a = .05 to test whether the mean percentage of 17- to 24-year-olds who are attending college is the same for the four geographic regions. |
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| m102654 | The following figure shows the standard normal curve and two t-curves. Which of the two t-curves has the larger degrees of freedom? Explain your answer. |
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| m102655 | The following histograms are based on different random samples of size 100 drawn from the same population
(i)
(ii)
(iii)
(a) Identify the midpoint of the class with the highest frequency in each of the three histograms.
(b) Using the class midpoints, what is the range of data shown in each histogram?
(c) Which of the histograms are more clearly skewed right?
(d) Based on your study of random sample in Chapter 1, is it surprising to see the variations in the samples as displayed in the histograms? The original population from which the samples were drawn is skewed right these properties equally well? |
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| m102656 | The following is an incomplete F table summarizing the results of a study of the variance of reaction times during a training exercise in a sample of 14 (n = 14) highly experienced, moderately experienced, and inexperienced athletes.
(a) Complete the F table.
(b) Compute eta-squared (η2).
(c) Is the decision to retain or reject the null hypothesis? |
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| m102657 | The following is an incomplete F table summarizing the results of a study of the variance of life satisfaction scores among unemployed, retired, part-time, and full-time employees.
(a) Complete the F table.
(b) Compute omega-squared (ω2).
(c) Is the decision to retain or reject the null hypothesis? |
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| m102658 | The following problem is based on information from an article by N. Key tz in the American Journal of Sociology (Vol. 53, pp. 470-480). Let x 5 age in years of a rural Quebec woman at the time of her fi rst marriage. In the year 1941, the population variance of x was approximately (2 = 5.1. Suppose a recent study of age at fi rst marriage for a random sample of 41 women in rural Quebec gave a sample variance s2 = 3.3. Use a 5% level of significance to test the claim that the current variance is less than 5.1. Find a 90% con fidence interval for the population variance?
Please provide the following information.
(a) What is the level of signi ficance? State the null and alternate hypotheses.
(b) Find the value of the chi-square statistic for the sample. What are the degrees of freedom? What assumptions are you making about the original distribution?
(c) Find or estimate the P-value of the sample test statistic.
(d) Based on your answers in parts (a) to (c), will you reject or fail to reject the null hypothesis of independence?
(e) Interpret your conclusion in the context of the application.
(f) Find the requested confi dence interval for the population variance or population standard deviation. Interpret the results in the context of the application. |
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| m102659 | The following problem is based on information from Archaeological Surveys of Chaco Canyon, New Mexico, by A. Hayes, D. Brugge, and W. Judge, University of New Mexico Press. A transect is an archaeological study area that is 1/5 mile wide and 1 mile long. A site in a transect is the location of a signifi cant archaeological find. Let x represent the number of sites per transect. In a section of Chaco Canyon, a large number of transects showed that x has a population variance (2 = 42.3. In a different section of Chaco Canyon, a random sample of 23 transects gave a sample variance s2 = 46.1 for the number of sites per transect. Use a 5% level of signi ficance to test the claim that the variance in the new section is greater than 42.3. Find a 95% confi dence interval for the population variance.
Please provide the following information.
(a) What is the level of signi ficance? State the null and alternate hypotheses.
(b) Find the value of the chi-square statistic for the sample. What are the degrees of freedom? What assumptions are you making about the original distribution?
(c) Find or estimate the P-value of the sample test statistic.
(d) Based on your answers in parts (a) to (c), will you reject or fail to reject the null hypothesis of independence?
(e) Interpret your conclusion in the context of the application.
(f) Find the requested confi dence interval for the population variance or population standard deviation. Interpret the results in the context of the ap |
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| m102660 | The following problem is based on information taken from Academe, Bulletin of the American Association of University Professors. Let x represent the average annual salary of college and university professors (in thousands of dollars) in the United States. For all colleges and universities in the United States, the population variance of x is approximately (2 = 47.1. However, a random sample of 15 colleges and universities in Kansas showed that x has a sample variance s2 = 83.2. Use a 5% level of signi ficance to test the claim that the variance for colleges and universities in Kansas is greater than 47.1. Find a 95% con fidence interval for the population variance.
Please provide the following information.
(a) What is the level of signi ficance? State the null and alternate hypotheses.
(b) Find the value of the chi-square statistic for the sample. What are the degrees of freedom? What assumptions are you making about the original distribution?
(c) Find or estimate the P-value of the sample test statistic.
(d) Based on your answers in parts (a) to (c), will you reject or fail to reject the null hypothesis of independence?
(e) Interpret your conclusion in the context of the application.
(f) Find the requested confi dence interval for the population variance or population standard deviation. Interpret the results in the context of the application. |
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| m102661 | The following problem is based on information taken from Accidents in North American Mountaineering (jointly published by The American Alpine Club and The Alpine Club of Canada). Let x represent the number of mountain climbers killed each year. The long-term variance of x is approximately (2 = 136.2. Suppose that for the past 8 years, the variance has been s2 = 115.1. Use a 1% level of signi ficance to test the claim that the recent variance for number of mountain climber deaths is less than 136.2. Find a 90% con fidence interval for the population variance.
Please provide the following information.
(a) What is the level of signi ficance? State the null and alternate hypotheses.
(b) Find the value of the chi-square statistic for the sample. What are the degrees of freedom? What assumptions are you making about the original distribution?
(c) Find or estimate the P-value of the sample test statistic.
(d) Based on your answers in parts (a) to (c), will you reject or fail to reject the null hypothesis of independence?
(e) Interpret your conclusion in the context of the application.
(f) Find the requested confi dence interval for the population variance or population standard deviation. Interpret the results in the context of the application. |
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| m102662 | The following table lists the distribution of degrees in psychology conferred by degree-granting institutions, by sex and year. These and similar data are reported by the National Center for Education Statistics (NCES) at http://nces.ed.gov/programs/digest/.
(a) Based on the data in this table, how has the number of degrees conferred in psychology changed by sex since 1970-1971?
(b) Is this a frequency distribution for grouped or ungrouped data? Explain. |
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| m102663 | The following table lists the number of text messages sent per day in a sample of college students and a sample of their parents.
(a) Compute the mean, the median, and the mode for the college students and parents data.
(b) Based on the shape of the distribution for each sample, which measure of central tendency is most appropriate for describing each sample? Explain how describing each sample with only the most appropriate measure might be misleading. |
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| m102664 | The following table presents information on the Kelley Blue Book s "10 Best Green Cars of 2013." Note that mpg and mpge are abbreviations for miles per gallon and miles per gallon equivalent, respectively. Identify the type of data provided by the information in each column of the table. |
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| m102665 | The following table provides statistics found in the document Science and Engineering Indicators, issued by the National Science Foundation, for a sample of 1564 adults. The first two columns of the table present an educational level distribution for the adults; the third column gives the percentage of the adults in each educational-level category who read an astrology report every day.
For one of these adults selected at random, determine the probability that he or she
a. Reads an astrology report every day.
b. Is not a high school graduate, given that he or she reads an astrology report every day.
c. Holds a baccalaureate degree or higher, given that he or she reads an astrology report every day. |
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| m102666 | The following table reports the price, horsepower, and ¼-mile speed for 16 popular sports and GT cars.
a. Find the estimated regression equation, which uses price and horsepower to predict ¼-mile speed.
b. Plot the standardized residuals against y. Does the residual plot support the assumption about e? Explain.
c. Check for any outliers. What are your conclusions? |
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| m102667 | The following table shows the total return and the number of funds for four categories of mutual funds.
a. Using the number of funds as weights, compute the weighted average total return for these mutual funds.
b. Is there any difficulty associated with using the "number of funds" as the weights in computing the weighted average total return in part (a)? Discuss. What else might be used for weights?
c. Suppose you invested $10,000 in this group of mutual funds and diversified the investment by placing $2000 in Domestic Equity funds, $4000 in International Equity funds, $3000 in Specialty Stock funds, and $1000 in Hybrid funds. What is the expected return on the portfolio? |
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| m102668 | The following table summarizes the cell, column, and row means for a 2 × 2 ANOVA.
(a) Which means reflect a main effect for Factor A?
(b) Which means reflect a main effect for Factor B?
(c) Which means reflect the interaction between Factors A and B? |
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| m102669 | The foraging behavior of the western pygmy-possum was investigated in the article "Strategies of a Small Nectarivorous Marsupial, the Western Pygmy-Possum, in Response to Seasonal Variation in Food Availability" (Journal of Mammalogy, Vol. 96, No. 6, pp. 1525-1535) by D. Morrant and S. Petit. The weights of adult male pygmy-possums in Australia are normally distributed with a mean of 8.5 g and a standard deviation of 0.3 g.
a. Sketch the normal curve for the pygmy-possum weights.
b. Find the sampling distribution of the sample mean for samples of size 4. Draw a graph of the normal curve associated with x̅.
c. Repeat part (b) for samples of size 9. |
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