Although there is a popular belief that herbal remedies such as ginkgo biloba and ginseng may improve learning and memory in healthy adults, these effects are usually not supported by well-controlled research (persson, bringlov, nilsson, and nyberg, 2004). in a typical study, a researcher obtains a sample of n = 16 participants and has each person take the herbal supplements every day for 90 days. at the end of the 90 days, each person takes a standardized memory test. for the general population, scores from the test form a normal distribution with a mean of μ = 50 and a standard deviation of σ=12 . the sample of research participants had an average of m = 54 .

a. assuming a two-tailed test, state the null hypothesis in a sentence that includes the two variables being examined.
b. using the standard 4-step procedure, conduct a two-tailed hypothesis test with α = .05 to evaluate the effect of the supplements.