In: Statistics and Probability
(1.) A normal population has a mean of µ = 100. A sample of n = 36 is selected from the population, and a treatment is administered to the sample. After treatment, the sample mean is computed to be M = 106. Assuming that the population standard deviation is σ = 12, use the data to test whether or not the treatment has a significant effect. Use a one tailed test.
Hypothesis:
Zcrit=
z test calculation:
Conclusion:
(2.) A mood questionnaire has been standardized so that the scores form a normal distribution with µ = 50 and σ = 15. A psychologist would like to use this test to examine how the environment affects mood. A sample of n = 25 individuals is obtained, and the individuals are given the mood test in a darkly painted, dimly lit room with plain metal desks and no windows. The average score for the sample is M = 43. Do the sample data provide sufficient evidence to conclude that the environment has a significant effect on mood? Use a two-tailed test.
Hypothesis:
Z crit=
z test calculation:
Conclusion: