Production process of average weight

1. The task of all hypothesis testing is to ____ H0 or ____ H0.

Answer
reject, fail to reject
reject, fail to accept
accept, fail to accept
fail to reject, discredit
accept, reject

12.When testing H0: m =m0 versus Ha: m ≠ m0, if H0 is rejected then the conclusion is:

Answer
Based on the sample data, there is sufficient evidence to conclude that m is equal to m0.
Based on the sample data, there is sufficient evidence to conclude that m is different from m0
Based on the sample data, there isn't sufficient evidence to conclude that m is equal to m0
Based on the sample data, there isn't sufficient evidence to conclude that m is different from m0
none of the above

17. Exhibit 8-2A production process is considered to be under control if the machine parts it makes have a mean length of 35.50 millimeters. Experience shows that the standard deviation of the lengths of the machine parts is .45 mm. Whether or not the process is in control, is decided each morning when the quality control technician takes a sample of 40 machine parts and tests, at the 5% level, whether μ = 35.50 mm.Refer to Exhibit 8-2. Is the process in control if the sample mean is 35.62 mm? What are the null and the alternative hypotheses?

Answer
H0: µ ≥ 35.50 Ha: µ < 35.50
H0: µ = 35.50 Ha: µ = 36.62
H0: µ = 35.50 Ha: µ ≠ 35.50
H0: µ ≤ 35.50 Ha: µ > 35.50
H0: µ > 35.50 Ha: µ = 35.50

18. Exhibit 8-3Two hundred people are randomly chosen at a shopping mall to taste-test a new brand of fruit drink. They are asked to rate the drink on a scale from 1 to 5, with 1 being very good and 5 being very bad. The results of the survey reveal that the average rating is 3.63 with a standard deviation of 1.22. The marketing division of the fruit drink distributor is only interested in selling this drink if the average rating is more than 3.5.Refer to Exhibit 8-3. What is the alternative hypothesis for testing whether the fruit drink distributor should sell this drink?

Answer
Ha: µ< 3.5
Ha: µ = 3.5
Ha: µ > 3.5
Ha: µ < 3.63
Ha: µ ≤ 3.5

19.Exhibit 8-8A production process is working normally if the average weight of a manufactured steel bar is at least 1.3 pounds. A sample of 50 steel bars yields a mean of 1.26 pounds with a standard deviation of .10 pounds. The question is whether there is sufficient evidence to indicate that the production process needs adjusting, using a .05 significance level. Refer to Exhibit 8-8. (Since the sample size is sufficiently large, use z.) The test procedure is to reject H0 if the value of the test statistic is

Answer
< -1.28 or > 1.28
> 1.646
< -1.645 or > 1.645
< -1.645
< -1.96 or > 1.96

20.Exhibit 8-7Records of student performance show that, in 1992, the average score in a statistics class was 79. In 2002, a statistics class of size 36 had an average score of 71 with a standard deviation of 19. Has the average score declined? Refer to Exhibit 8-7. Testing at the .05 level of significance, what is the conclusion? (Since the sample size is sufficiently large, use z.)

Answer
Based on the sample data, there is sufficient evidence to conclude that the average score in 2002 was less than 79.
Based on the sample data, there is sufficient evidence to conclude that the average score in 2002 was 79.
Based on the sample data, there isn't sufficient evidence to conclude that the average score in 2002 was less than 79.
Based on the sample data, there isn't sufficient evidence to conclude that the average score in 2002 was 79.
none of the above