A mood questionnaire has been standardized so that the scores from a normal distribution with µ = 50 and ? = 15. A psychologist would like to use this test to examine how the environment affects mood. A sample n = 25 individuals is obtained, and the individuals are given the mood test in a darkly painted, and dimly lit room with plain metal desks and no windows. The average score for the sample is M = 49. (? = .05)
What is the test statistic?
z = -1/3
z = 1/3
t = -1/3
t = 1/3