The management of a chain electronic store would like to develop a model for predicting the weekly sales (in thousand of dollars) for individual stores based on the number of customers who made purchases. A random sample of 12 stores yields the following results: Sales (Thousands of Dollars) Customers 907 11.20 926 11.05 713 8.21 741 9.21 780 9.42 898 10.08 510 6.73 529 7.02 460 6.12 872 9.52 650 7.53 603 7.25 True or False: Referring to Table 12-10, the null hypothesis for testing whether the number of customers who make a purchase effects weekly sales cannot be rejected if a 1% probability of committing a Type I error is desired. Select one: O True O Fake

The price of a share of stock divided by the company's estimated future earnings per share is called the P/E ratio. High P/E ratios usually indicate "growth" stocks, or maybe stocks that are simply overpriced. Low P/E ratios indicate "value" stocks or bargain stocks. A random sample of 51 of the largest companies in the United States gave the following P/E ratiost. 9 20 11 35 19 13 15 21 29 53 16 26 21 14 21 27 10 12 47 14 40 18 60 72 33 14 8 49 5 16 8 19 12 31 67 51 26 18 17 20 19 13 25 23 27 44 20 27 19 18 32 (a) Use a calculator with mean and sample standard deviation keys to find the sample mean x and sample standard deviation s. (Round your answers to one decimal place.) (b) Find a 90% confidence interval for the P/E population mean u of all large U.S. companies. (Round your answers to one decimal place.) lower limit upper limit (c) Find a 99% confidence interval for the P/E population mean u of all large U.S. companies. (Round your answers to one decimal place.) lower limit upper…

Is there a relation between incidents of child abuse and number of runaway children? A random sample of cities (over 10,000 population) gave the following information about the number of reported incidents of child abuse and the number of runaway children. (Reference: Federal Bureau of Investigation, U.S. Department of Justice.) City 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 Abuse cases 113 33 41 60 52 99 31 56 15 67 106 59 45 74 84 Runaways 648 188 285 687 421 590 284 277 162 473 600 432 317 580 592 Use a 1% level of significance to test the claim that there is a monotone-increasing relationship between the ranks of incidents of abuse and number of runaway children. (a) Rank-order abuse using 1 as the largest data value. Also rank-order runaways using 1 as the largest data value. Then construct a table of ranks to be used for a Spearman rank correlation test. City Abuse CasesRank x RunawaysRank y d = x - y d2 123456789101112131415 Σd2 =  (b) What is the level of…

Last school year, the student body of a local university consisted of 35% freshmen, 24% sophomores, 26% juniors, and 15% seniors. A sample of 300 students taken from this year's student body showed the following number of students in each classification. Freshmen 90 Sophomores 60 Juniors 90 Seniors 60 We are interested in determining whether or not there has been a significant change in the classifications between the last school year and this school year. The calculated value for the test statistic equals   a. 0.5444   b. 2.789   c. 10.989   d. 15.231

The mean birthweight of an infant is thought to be associated with the smoking status of the mother during the first trimester of the pregnancy. Consider the following data from mothers divided into four categories according to smoking habits, and the corresponding birthweights of their children. Group 1: Mother is a non smoker (NON): 7.5, 6.2, 6.9, 7.4, 9.2, 8.3, 7.6 Group 2: Mother is an ex-smoker (EX): 5.8, 7.3, 8.2, 7.1, 7.8 Group 3: Mother is a current smoker, smokes less than 1 pack per day (CUR < 1) 5.9, 6.2, 5.8, 4.7, 8.3, 7.2, 6.2 Group 4: Mother is a current smoker, smokes more than or equal to 1 pack per day (Cur ≥ 1) 6.2, 6.8, 5.7, 4.9, 6.2, 7.1, 5.8, 5.4 Using Stata test whether or not the mean birthweights are equal across all four groups at the alpha = 0.05 level. What are your null and alternative hypothesis? Ο HO: μ_1== μ_2 HA: μ_1=\= μ_2 O HO: μ_i== u_j for all i and j HA: μ_i=\= μ_j for all i and j O HO: μ_i == μ_j for all i and j HA: μ_i=\= μ_j for at least one i,j…

How do the average weekly incomes of electricians and carpenters compare? A random sample of 17 regions in the United States gave the following information about average weekly income (in dollars). (Reference: U.S. Department of Labor, Bureau of Labor Statistics.) Region 1 2 3 4 5 6 7 8 9 Electricians 464 715 597 464 736 694 744 571 806 Carpenters 542 813 513 476 688 503 789 653 474 Region 10 11 12 13 14 15 16 17 Electricians 592 594 702 579 868 598 597 654 Carpenters 489 647 676 384 817 605 556 505 Does this information indicate a difference (either way) in the average weekly incomes of electricians compared to those of carpenters? Use a 5% level of significance. (a) What is the level of significance? (b) Compute the sample test statistic.  (c) Find the P-value of the sample test statistic.

Used car auctions give car dealers an opportunity to increase their used car inventory by purchasing cars used as rental cars, assigned to company executives, and other similar activities. Suppose population 1 is all black cars sold at used car auctions, and population 2 is all white cars sold at used car auctions. Of interest is to estimate the difference in the mean sale price of all black cars sold at used car auctions and the mean sale price of all white cars sold at used car auctions. Based on this, using both the appropriate symbol and in words, state the one parameter of interest.

Pavan

Hospitals In a study of births in New York State, data were collected from four hospitals coded as follows: (1) Albany Medical Center; (1438) Bellevue Hospital Center; (66) Olean General Hospital; (413) Strong Memorial Hospital. Does it make sense to calculate the average (mean) of the numbers 1, 1438, 66, and 413?