8 Questions 25-28 are related to the following 9 A large group ofstudents took a statistics test. 0 The mean score, from the scale of 100, was 75.2 with a standard deviation of 7.4-5 '1 The test scores have a bell-shaped distribution. 2 25 Students who scored less than 60 failed the test. 3 What fraction of students failed the test? 4 a 0.02 0? 5 b 0.02 ?5 6 c 0.03 6? ? d 0.0490 8 9 26 In the previous question, 95% of test scores are within 1 from the mean test score. 0 a 16.9 1 b 16.1 2 c 15.3 3 d 14.6 4 5 2? Ifthe range of scores for a C is 68 to '?8 6 what fraction of students received a C? ? a 0.51 8? 8 b 0.49 88 9 c 0.4? 96 0 d 0.46 11 1 2 28 If the minimum score for the letter grade B is '?9 3 what fraction of students received a grade of B or higher. 4 a 0.30 50 5 b 0.28 ?? 6 c 0.2? 15 ? d 0.25 61 8 9 29 What should the minimum score be set at so that a grade ofA is given to the top 7.5% oftest scores? 0 a 89 1 b 88 2 c 86 3 d 84 4 5 Questions 29 and 30 are related 6 30 A large number of students took a departmental math test. ? 6.8% of students scored 88 or more from the scale of 100. 8 The scores have a bell-shaped distribution with a standard deviation of '?.8 9 If the minimum score to pass the test is 62 what fraction of the students failed the test? 0 a 0.02 09 1 b 0.02 62 2 c 0.03 2? 3 d 0.0409 4 5 31 The middle interval which includes 95% of the test scores is to . [Round the 6 scores to the nearest integer.) ? a 62 91 8 b 61 92 9 c 60 93 0 d 59 94 '1 32 9-0393 The passenger car tires manufactured by Greatyear Co. last on average 66,800 it = 66,800 Of all tires manufactured by Greatyear 15% last more than ?5,5 00 miles. Greatyear is considering a guarantee that will provide a dis count on replacement tires if the original tires do not reach the guaranteed mileage. What should the guaranteed mileage be if Greatyear wants no more than {at most} 5% of the tires be eligible for the discount guarantee? 52393 555201 51501 593397Ir