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For Problems 3–11, please provide the following information.
- (a) What is the level of significance? 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 confidence interval for the population variance or population standard deviation. Interpret the results in the context of the application.
In each of the following problems, assume a
Mountain Climbing: Accidents 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 σ2 = 136.2. Suppose that for the past 8 years, the variance has been s2 = 115.1. Use a 1% level of significance to test the claim that the recent variance for number of mountain climber deaths is less than 136.2. Find a 90% confidence interval for the population variance.
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Chapter 10 Solutions
WebAssign Printed Access Card for Brase/Brase's Understandable Statistics: Concepts and Methods, 12th Edition, Single-Term
- According to health professionals, a person’s weight is expected to increase with age. To examine that statement, a nutritionist collected data from 11 random females from different age categories between the ages of 21 and 43. In the following table, x is the age of a person and y is the weight in pounds. x, age 21 24 27 29 31 33 35 38 40 42 43 y, weight in lb 121.4 122.3 130.3 131.7 133.3 134.6 136.7 138.4 140.3 142.0 145.1 Select the correct graph of the least-squares line on a scatter diagram.arrow_forwardLet x be a random variable that represents the percentage of successful free throws a professional basketball player makes in a season. Let y be a random variable that represents the percentage of successful field goals a professional basketball player makes in a season. A random sample of n = 6 professional basketball players gave the following information. x 82 69 73 84 74 64 y 42 48 46 46 46 42 Verify that ∑x =446, ∑y =270, ∑x2 =33,442, ∑y2 =12,180, ∑xy =20,070, and r = 0, and find the critical value for a test using a 5% level of significance claiming that ρis not equal than zero. Round your answer to three decimal places.arrow_forwardLet x be a random variable that represents the percentage of successful free throws a professional basketball player makes in a season. Let y be a random variable that represents the percentage of successful field goals a professional basketball player makes in a season. A random sample of n = 6 professional basketball players gave the following information. x 75 72 75 81 74 81 y 46 39 42 47 49 50 Verify that Se ࣈ 3.591,a ࣈ –10.145, bࣈ0.729, and , and find the predicted percentage of successful field goals for a player with x= 88%successful free throws. Round your answer to the nearest tenth of a percentarrow_forward
- An editor wants to analyze if there is a significant difference in the ratings of books in four different genres. Random samples of book ratings were collected for four different genres. The editor recorded ratings in a 0 to 10 scale in the following table. Fiction Novel Biography Science&Technology 8.5 8.4 6.2 9.1 5.3 5.3 5.5 4.3 7.7 4.2 7.0 9.7 5.1 9.8 9.3 5.2 6.9 8.6 6.7 7.9 4.8 7.1 6.9 8.4 Shall we reject or not reject the claim that there are no differences among the population means of book ratings for the different genres? Use.arrow_forwardPeggy conducted a study to identify the randomness of rainy days in fall. For 15 days, she recorded whether it rained that day or not. They denoted a rainy day with the letter R, a day without rain with the letter N. R N N R R N N R R N N R R R R Test the sequence for randomness. Use .arrow_forwardConsider the grades for the math and history exams for 10 students on a scale from 0 to 12 in the following table. Student Math History 1 4 8 2 5 9 3 7 9 4 12 10 5 10 8 6 8 5 7 9 6 8 9 6 9 11 9 10 7 10 Compute the Spearman correlation coefficient. Round your answer to three decimal places.arrow_forward
- To compare two elementary schools regarding teaching of reading skills, 12 sets of identical twins were used. In each case, one child was selected at random and sent to school A, and his or her twin was sent to school B. Near the end of fifth grade, an achievement test was given to each child. The results follow: Twin Pair 1 2 3 4 5 6 School A 169 157 115 99 119 113 School B 123 157 112 99 121 122 Twin Pair 7 8 9 10 11 12 School A 120 121 124 145 138 117 School B 153 90 124 140 142 102 Suppose a sign test for matched pairs with a 1% level of significance is used to test the hypothesis that the schools have the same effectiveness in teaching reading skills against the alternate hypothesis that the schools have different levels of effectiveness in teaching reading skills. Let p denote portion of positive signs when the scores of school B are subtracted from the corresponding scores of school…arrow_forwardA horse trainer teaches horses to jump by using two methods of instruction. Horses being taught by method A have a lead horse that accompanies each jump. Horses being taught by method B have no lead horse. The table shows the number of training sessions required before each horse performed the jumps properly. Method A 25 23 39 29 37 20 Method B 41 21 46 42 24 44 Method A 45 35 27 31 34 49 Method B 26 43 47 32 40 Use a rank-sum test with a5% level of significance to test the claim that there is no difference between the training sessions distributions. If the value of the sample test statistic R, the rank-sum, is 150, calculate the P-value. Round your answer to four decimal places.arrow_forwardA data processing company has a training program for new salespeople. After completing the training program, each trainee is ranked by his or her instructor. After a year of sales, the same class of trainees is again ranked by a company supervisor according to net value of the contracts they have acquired for the company. The results for a random sample of 11 salespeople trained in the last year follow, where x is rank in training class and y is rank in sales after 1 year. Lower ranks mean higher standing in class and higher net sales. Person 1 2 3 4 5 6 x rank 8 11 2 4 5 3 y rank 7 10 1 3 2 4 Person 7 8 9 10 11 x rank 7 9 10 1 6 y rank 8 11 9 6 5 Using a 1% level of significance, test the claim that the relation between x and y is monotone (either increasing or decreasing). Verify that the Spearman rank correlation coefficient . This implies that the P-value lies between 0.002 and 0.01. State…arrow_forward
- Sand and clay studies were conducted at a site in California. Twelve consecutive depths, each about 15 cm deep, were studied and the following percentages of sand in the soil were recorded. 34.4 27.1 30.8 28.0 32.2 27.6 32.8 25.2 31.4 33.5 24.7 28.4 Converting this sequence of numbers to a sequence of symbols A and B, where A indicates a value above the median and B denotes a value below the median gives ABABABABAABB. Test the sequence for randomness about the median with a 5% level of significance. Verify that the number of runs is 10. What is the upper critical value c2? arrow_forwardSand and clay studies were conducted at a site in California. Twelve consecutive depths, each about 15 cm deep, were studied and the following percentages of sand in the soil were recorded. 34.4 27.1 30.8 28.0 32.2 27.6 32.8 25.2 31.4 33.5 24.7 28.4 Converting this sequence of numbers to a sequence of symbols A and B, where A indicates a value above the median and B denotes a value below the median gives ABABABABAABB. Test the sequence for randomness about the median with a 5% level of significance. Verify that the number of runs is 10. What is the upper critical value c2?arrow_forward29% of all college students major in STEM (Science, Technology, Engineering, and Math). If 46 college students are randomly selected, find the probability thata. Exactly 11 of them major in STEM. b. At most 12 of them major in STEM. c. At least 11 of them major in STEM. d. Between 11 and 15 (including 11 and 15) of them major in STEM.arrow_forward
- Glencoe Algebra 1, Student Edition, 9780079039897...AlgebraISBN:9780079039897Author:CarterPublisher:McGraw HillCollege Algebra (MindTap Course List)AlgebraISBN:9781305652231Author:R. David Gustafson, Jeff HughesPublisher:Cengage Learning
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