
Concept explainers
Wilcoxon Signed-Rank Test for n > 30 When you are performing a Wilcoxon signed-rank test and the
In Exercises 9 and 10, perform the Wilcoxon signed-rank test using the test statistic for n > 30.
9. Fuel Additive A petroleum engineer wants to know whether a certain fuel additive improves a car’s gas mileage. To decide, the engineer records the gas mileages (in miles per gallon) of 33 randomly selected cars with and without the fuel additive. The table shows the results. At a = 0.10, can the engineer conclude that the gas mileage is improved?

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Chapter 11 Solutions
Elementary Statistics: Picturing the World (7th Edition)
- A restaurant serves three fixed-price dinners costing $12, $15, and $20. For a randomly selected couple dining at this restaurant, let X = the cost of the man's dinner and Y = the cost of the woman's dinner. The joint pmf of X and Y is given in the following table. p(x, y) 15 y 12 20 12 0.05 0.10 0.35 x 15 0.00 0.20 0.10 20 0.05 0.05 0.10 (a) Compute the marginal pmf of X. x 12 Px(x) Compute the marginal pmf of Y. y Pyly) 12 15 20 15 20 (b) What is the probability that the man's and the woman's dinner cost at most $15 each? (c) Are X and Y independent? Justify your answer. X and Y are independent because P(x, y) = Px(x) · Py(y). X and Y are not independent because P(x, y) =Px(x) · Pyly). X and Y are not independent because P(x, y) * Px(x) · Py(y). X and Y are independent because P(x, y) * Px(x) · Py(y). (d) What is the expected total cost, in dollars, of the dinner for the two people? $ (e) Suppose that when a couple opens fortune cookies at the conclusion of the meal, they find the…arrow_forwardLet X = the time between two successive arrivals at the drive-up window of a local bank. If X has an exponential distribution with λ = 1, (which is identical to a standard gamma distribution with α = 1), compute the following. (If necessary, round your answer to three decimal places.) (a) the expected time between two successive arrivals (b) the standard deviation of the time between successive arrivals (c) P(X ≤ 1) (d) P(2 ≤ X ≤ 4) You may need to use the appropriate table in the Appendix of Tablesarrow_forwardIn each case, determine the value of the constant c that makes the probability statement correct. (Round your answers to two decimal places.) USE SALT (a) (c) 0.9842 (b) P(0 ≤ Z ≤ c) = 0.3051 (c) P(CZ) = 0.1335 You may need to use the appropriate table in the Appendix of Tables to answer this question.arrow_forward
- Find aarticle about confidence intervals and post a short summary.arrow_forwardFind a video or article about confidence intervals and post a short summary and a link.arrow_forwardprovide analysis based on the data on the image answering the following: Define Regression as a method to establish whether the pairs of data (observations) follow a straight line. Here, you are required to perform a regression between Y and X for the purpose of prediction. Show the regression line and then discuss the following: Run an OLS regression to test the significance of the theoretical signs expected What is the Y-intercept Compute the slope R square and r (correlation coefficient) Is the explanatory variable significant at the 5% level? That is, what is the “t” value? Estimate the regression equation and graphically show the regression line Compute the p-value and is it less than the 5% cut off point for being significant?arrow_forward
- Holt Mcdougal Larson Pre-algebra: Student Edition...AlgebraISBN:9780547587776Author:HOLT MCDOUGALPublisher:HOLT MCDOUGALFunctions and Change: A Modeling Approach to Coll...AlgebraISBN:9781337111348Author:Bruce Crauder, Benny Evans, Alan NoellPublisher:Cengage Learning


