Q1. A researcher wants to determine the sample size necessary to adequately conduct a study to estimate the population mean to within 5 points. The range of population values is 80 and the researcher plans to use a 90% level of confidence. The sample size should be at least _______.
A. 44
B. 62
C. 216
D. 692
Q2. Restaurateur Daniel Valentine is evaluating the feasibility of opening a restaurant in Richmond. The Chamber of Commerce estimates that ‘Richmond families, on the average, dine out at least 3 evenings per week'. Daniel plans to test this hypothesis at the 0.01 level of significance. His random sample of 81 Richmond families produced a mean of 2.7. Assuming that the population standard deviation is 0.9 evenings per week, the appropriate decision is __________.
A. do not reject the null hypothesis
B. reject the null hypothesis
C. reduce the sample size
D. increase the sample size
Q3. When the rod shearing process at Newcastle Steel is ‘in control' it produces rods with a mean length of 120 cm. Periodically, quality control inspectors select a random sample of 36 rods. If the mean length of sampled rods is too long or too short, the shearing process is shut down. The last sample showed a mean of 120.5 cm. The population standard deviation is 1.2 cm. Using α = 0.05, the appropriate decision is _________.
A. do not reject the null hypothesis and shut down the process
B. do not reject the null hypothesis and do not shut down the process
C. reject the null hypothesis and shut down the process
D. reject the null hypothesis and do not shut down the process
Q4. When a researcher fails to reject a false null hypothesis, a ______ error has been committed.
A. Type II error
B. Type I error
C. sampling error
D. powerful error
Q5. Auckland First Bank's policy requires consistent, standardised training of employees at all branches. Consequently, David Marshall, Human Resources Manager, orders a survey of mean employee training time in the Southern region (population 1) and the Northern region (population 2). His staff randomly selected personnel records of 81 employees from each region, and reported the following: x 1 = 30 hours and x 2 = 27 hours. Assume that σ1 = 6, and σ2 = 6. With a two-tail test and α = .05, the appropriate decision is ______________.
A. reject the null hypothesis µ1 - µ2 = 0
B. accept the alternate hypothesis µ1 - µ2< 0
C. reject the null hypothesis µ1 - µ2≠ 0
D. do not reject the null hypothesis µ1 - µ2 > 0