Question

FOR NEXT 5 QUESTIONS USE THE FOLLOWING DIRECTION: The average life of light bulbs produced by SABA Electric Co. is expected to be normally distributed with the mean service life of 950 hours and standard deviation of 100 hours. A random sample of 100 bulbs is tested and it has a mean life of 910 hours.

Can researcher conclude that the mean service life of the bulbs is less than the expectation? H0 is null hypothesis, and Ha is alternative hypothesis. Which method can researcher use to check the 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

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

What significance level (α) do you suggest for this test?
A. Level of significance = 100
B. Level of significance = 0%
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 given data?
A. Reject H0. The mean service life of the bulbs is less than the expectation.
B. Do not reject H0. The mean service life of the bulbs is less than the expectation.
C. Reject H0. The mean service life of the bulbs is not less than the expectation
D. Do not reject H0. The mean service life of the bulbs is not less than the expectation
E. None of the above.

Answer 1