Although there is a popular belief that herbal remedies such as Gingko biloba and Ginseng may improve learning and memory in healthy adults, these effects are usually not supported by well-controlled research (Persson, Bringlov, Nilsson, & Nyberg, 2004). In a recent study, a researcher obtained a sample ofn = 16 participants and had each person take the herbal supplement every day for 90 days. At the end of the 90 days, each person took a standardized memory test. For the general population, the scores on this memory test form a normal distribution with a = 50 and = 12. The sample of research participants had an average score of M = 54.

Research Question

Did the use of herbal supplements lead to improvements in memory?

Alpha level of = .01

Critical value = +2.57 or -2.57

Which of the following correctly represents the calculation and answer for the test statistic for this hypothesis test?

1. 50-54

z test = 12 = -1.33

16

2. 54-50

z test = 12 = 0.33

3. 50-54

z test = 12 = -0.33