A90 ODD ANSWERS 7. (a) H0: m1 = m2 = m3 Ha: At least one mean is different from the others. (claim) (b) F0 = 6.36; Rejection region: F 7 6.36 (c) 16.11 (d) Reject H0. (e) There is enough evidence at the 1% level of significance to conclude that at least one mean vacuum cleaner weight is different from the others. 9. (a) H0: m1 = m2 = m3 = m4 Ha: At least one mean is different from the others. (claim) (b) F0 = 2.84; Rejection region: F 7 2.84 (c) 0.62 (d) Fail to reject H0. (e) There is not enough evidence at the 5% level of significance to conclude that at least one mean age is different from the others. 11. (a) H0: m1 = m2 = m3 = m4 (claim) Ha: At least one mean is different from the others. (b) F0 = 2.28; Rejection region: F 7 2.28 (c) 3.67 (d) Reject H0. (e) There is enough evidence at the 10% level of significance to reject the claim that the mean scores are the same for all regions. 13. (a) H0: m1 = m2 = m3 = m4 = m5 = m6 Ha: At least one mean is different from the others. (claim) (b) F0 = 2.53; Rejection region: F 7 2.53 (c) 2.913 (d) Reject H0. (e) There is enough evidence at the 5% level of significance to conclude that at least one mean salary is different from the others. 15. Fail to reject all null hypotheses. The interaction between the advertising medium and the length of the ad has no effect on the rating and therefore there is no significant difference in the means of the ratings. 17. Fail to reject all null hypotheses. The interaction between age and gender has no effect on GPA and therefore there is no significant difference in the means of the GPAs. 19. CVScheffe´ = 12.72 (1, 2) S4.95 SNo difference (1, 3) S11.61 SNo difference (2, 3) S31.73 SSignificant difference 21. CVScheffe´ = 17.48 (1, 2) S10.06 SNo difference (1, 3) S42.99 SSignificant difference (1, 4) S21.15 SSignificant difference (1, 5) S29.00 SSignificant difference (2, 3) S12.47 SNo difference (2, 4) S3.10 SNo difference (2, 5) S5.58 SNo difference (3, 4) S2.23 SNo difference (3, 5) S1.26 SNo difference (4, 5) S0.19 SNo difference Uses and Abuses for Chapter 10 (page 570) 1 – 2. Answers will vary. Review Exercises for Chapter 10 (page 572) 1. (a) H0: The age distribution of U.S. physicians is 20% are less than 40, 26% are 40 – 49, 28% are 50 – 59, 22% are 60 – 69, and 4% are 70 and older. Ha: The age distribution of U.S. physicians differs from the expected distribution. (claim) (b) x2 0 = 13.277; Rejection region: x 2 7 13.277 (c) 14.662 (d) Reject H0. (e) There is enough evidence at the 1% level of significance to conclude that the distribution of the ages differs from the expected distribution. 3. (a) H0: The distribution of opinions of golfers about what irritates them the most is 65.1% slow play, 18.5% poor course conditions, 11.1% poor etiquette, 5.3% high green fees. (claim) Ha: The distribution of opinions of golfers about what irritates them the most differs from the expected distribution. (b) x2 0 = 7.815; Rejection region: x 2 7 7.815 (c) 4.256 (d) Fail to reject H0. (e) There is not enough evidence at the 5% level of significance to conclude that the distribution of opinions of golfers about what irritates them the most differs from the expected distribution. 5. (a) Years of full-time teaching experience Less than 3 years 3 – 9 years 10 – 20 years 20 years or more Elementary 93.1293.4423.7240.8 Secondary 216.9 683.6 987.3 561.2 (b) H0: The years of full-time teaching experience is independent of level of instruction. Ha: The years of full-time teaching experience is dependent on level of instruction. (claim) (c) d.f. = 3; x2 0 = 11.345; Rejection region: x 2 7 11.345 (d) 2.275 (e) Fail to reject H0. (f) There is not enough evidence at the 1% level of significance to conclude that the years of full-time teaching experience is dependent on level of instruction. 7. (a) Vertebrate group Status Mammals Birds Reptiles Amphib- ians Fish Endangered 132.43 117.72 48.79 17.04 72.02 Threatened 38.57 34.2814.21 4.9620.98 (b) H0: A species’ status is independent of vertebrate group. (claim) Ha: A species’ status is dependent on vertebrate group. (c) d.f. = 4; x2 0 = 9.488; Rejection region: x 2 7 9.488 (d) 44.751 (e) Reject H0. (f) There is enough evidence at the 5% level of significance to reject the claim that a species’ status (endangered or threatened) is independent of vertebrate group. 9. 2.295 11. 2.39 13. 2.06 15. 2.08
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