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Question

Some researchers claim that herbal supplements such as ginseng or ginkgo biloba enhance human memory. To test this claim, a researcher selects a sample of *n* = 25 college students. Each student is given a ginkgo biloba supplement daily for six weeks and then all the participants are given a standardized memory test. For the population, scores on the test are normally distributed with *µ* = 70 and *σ* = 15. The sample of *n* = 25 students had a mean score of *M* = 75.

a. Are the data sufficient to conclude that the herb has a significant effect on memory? Use a two-tailed test with *α* = .05.

b. Compute Cohen’s *d* for this study.

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Statistics

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