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 [2002]: 835–840), elderly adults were as- signed at random to either a treatment group 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 function. Summary values are given in the following table. n Ginkgo Placebo 104 5.6 .6 115 5.5 .6 Based on these results, is there evidence that taking 40 mg of ginkgo three times a day is effective in increasing mean performance on the Wechsler Memory Scale? Test the rel- evant hypotheses using a = .05.