Suppose that we know that a population has a mean of μ =10 and standard deviation σ = 2 . We take all possible
random samples of size n = 16 from this population.
13. What will be the value of the mean of all these sample means.
14. What will be the value of the standard deviation of all these sample means.
A Math teacher believes the math ability of her students has improved in the last years. The last report on a National
Mathematics Proficiency Test states that nationwide the test has a mean of μ = 75 and a standard deviation of σ = 12. The
teacher applies this Math Proficiency Test to her class of n= 50 students and finds an average score of X = 80. She wants
to test if this sample mean is evidence that her students come from a population with a mean larger than the national average.
Use a Z-test for one sample to test the teacher’s hypothesis. Use an alpha of .05
15. State the alternative hypothesis and null hypotheses
16. State the test-statistic to use (and the equation) and its sampling distribution.
17. Define the rejection regions and state the decision rule (the Zcritical)
18. Compute the test-statistic (the value of Zobt) and make the decision of reject or retain the null hypothesis.
19. Are these students performing better than the national average?

Progress so far?

none. um well the first 12 problems. :)

Progress so far on 13 - 19? Where are you stuck on each one?