Let’s say that you are interested in comparing scores on the GRE-Psychology exam

1. Let’s say that you are interested in comparing scores on the GRE-Psychology exam (GRE- P) of ISU Psychology majors to the population mean for all students who took the GRE-P last year nationwide. First assume that we don’t know the actual population mean for all students who took the exam nationwide but we want to create a 95% confidence
interval for an estimate of the population mean. Now, assume that we have a sample of 97 ISU Psychology students who took the test and had a mean GRE-P score of 159.2 and a standard deviation (s) of 14.6.
a) Start by finding the standard error, sX Check your formulas from lecture or lab – this is based on the sample size and the sample standard deviation.
b) Next, find the 95% confidence interval for the population mean (hint: one piece of information you’ll need for the formula is the standard error that you just found above).
c) Finally, we will use the 95% confidence interval you just found to conduct a hypothesis test. Let’s say that you just gained access to the population mean of all students nationwide who took the GRE-P last year and that population mean is 156.1. Does our sample’s mean from 97 ISU Psychology students differ significantly from the population mean of 156.1? Indicate whether you should reject the null or fail to reject the null (the null states that there is no significant difference between the population mean and the sample mean).