HW 3 Exemplars

HW 3 Exemplars - Exemplars for the Homework Problems from...

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Exemplars for the Homework Problems from Section 3.2 Required for Homework #3 Chapter 3, Section 3.2: Problems 18 and 19. For measures of variability, problem parts with the following additional questions (from HW #3): a. Of the sampled data, what value is expected? b. In general, what value is expected for the population that was sampled? c. How strongly should this value be expected? (Hint: Use the CV test.) d. Is the mean a good representation of the sample data, yes or no? (Show this with the CV test.) e. Do the data show high or low variability about the mean? (Hint: Use the CV test.) f. Is the data sample skewed or not? If it is, which way? Why? g. Describe the shape of the inner half of the ranked data. (That is, answer the question: Is the inner half of the data tightly clustered under a narrow peak or broadly scattered under a broad hump?) (Hint: Use the IQR/R test.) h. There is a very high chance (about a 95% chance) that the margin of error in the expected value of the sampled data is how large? In other words, chances are very high that the sample mean is off from the true (population) mean by at most how much? (Hint: MoE = 2×s/√n).) Chap 3 recitation problems 1 © Harvey Singer 2009

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18. Excel calculations: stat Daily rate (\$) ranked x dev dev^2 Western ci 43 30 -8 64 35 30 = Q1 -8 64 34 34 -4 16 58 35 = median -3 9 30 36 -2 4 30 43 = Q3 5 25 36 58 20 400 0 582 = SOS 97.00 = s^2 9.85 = s mean 38 38 38 median 35 mode 30 2x midrange 44 midquartile 36.5 range 28 28 IQR 13 IQR/R 0.464 s^2 97.00 12.3 s 9.85 3.5 CV 0.259 0.092 a. 266 \$38 7 i x x n Σ = = = per day 2 2 ( ) 582 97 1 6 i x x s n Σ - = = = - 97 \$9.85 s = = b. The mean car-rental rate per day is \$38 for both eastern and western U.S. cities. However, Eastern cities show a greater variation in rates per day. This greater variation is most likely due to the inclusion of the most expensive city (New York) in the Eastern city sample. Additional questions: a. Of the sampled data, what value is expected? Of the seven sampled eastern U.S. cities, expect a car rental rate of \$38 per day. Chap 3 recitation problems 2 © Harvey Singer 2009
(For the sampled western U.S. cities, expect a car rental rate of \$38 per day. So it’s expected to cost as much in the seven sampled western U.S. cities as in the seven sampled eastern U.S. cities.) b. In general, what value is expected for the population that was sampled? In general, expect a car rental rate of \$38 per day in any eastern U.S. city.

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This note was uploaded on 02/19/2011 for the course OM 210 taught by Professor Singer during the Spring '08 term at George Mason.

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HW 3 Exemplars - Exemplars for the Homework Problems from...

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