he diameter of a spindle in a motor is supposed to be 40 mm with standard deviation of 0.5 mm. If the spindle is either too small or too large, the motor will not work properly. The manufacturer measures the diameter in a sample of 100 motors to determine whether the mean diameter has moved away from the target, and finds that average is 40.3 mm. Which method researcher can use to check her idea?

• A.Hypothesis testing - Z test
• B.Hypothesis testing - t test
• C.Sample size estimation for average
• D.None of the above

If she conducts hypothesis testing, she has to consider:

• A.one-tailed test
• B.two-tailed test
• C.one-tailed test because sample size is large
• D.two-tailed test because sample size is large

Which set of ideas can she formulate for her research:

• A.H0: = 40 and Ha: is not equal to 40
• B.H0: = 40 and Ha: <40
• C.H0: < 40 and Ha: > 40
• D.H0: = 40 and Ha: > 40

What significance level do you choose for this test?

• A.Level of significance = 50
• B.Level of significance = 2.5
• C.Level of significance = 95%
• D.Level of significance = 99%
• E.None of the above

Which one of the following is a correct conclusion based on the data given? Use 5% significance level.

• A.Reject H0. The mean diameter has moved away from the target of 40.3 mm.
• B.Do not reject H0. The mean diameter has moved away from the target of 40.3 mm.
• C.Reject H0. The mean diameter has moved away from the target of 40 mm.
• D.Do not reject H0. The mean diameter has moved away from the target of 40 mm.
• E.None of the above