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Many people take ginkgo supplements advertised to improve memory. Are these over-the-counter supplements effective? In a study reported in the paper “Ginkgo for memory Enhancement” (Journal of the American Medical Association), elderly adults were assigned at random to either a treatment or a control group. The 104 participants who were assigned to the treatment group took 40 mg of ginkgo three times a day for six weeks. The 115 participants assigned to the control group took a placebo pill three times a day for six weeks. At the end of six weeks, the Wechsler Memory Scale (a test of short-term memory) was administered. Higher scores indicate better memory
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Based on these results, we want to find whether there is evidence that taking 40 mg of ginkgo three times a day is effective in increasing
A) Calculate the test statistic for the test above. (round test statistic to 2 decimal places) __________________
B) What is the cutoff value for the rejection region? Use significance level 0.05. (round to 2 decimal places) _________________
C) What's your decision on the hypothesis test above? Use significance level 0.05. __________________
(type Reject for Reject Ho, type FTR for Fail to Reject Ho)
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