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.

If the researchers use an alpha level of = .01, the critical value they should use is

1. -1.64

2. +1.64

3. +1.96 or -1.96

4. -2.33

5. +2.33

6. +2.57 or -2.57

7. -3.08

8. +3.08

9. +3.32 or -3.32