An aerobic dance teacher wanted to know whether two workouts per week of 30 minutes each were enough to increase VO₂max in sedentary middle- aged women.The teacher proposed to compare VO₂max of some women who had been in the aerobic dance classes for 6 months with VO₂max of a group of sedentary women.Based on related literature, the teacher estimated that VO₂max would be about 7 milliliters per kilogram per minute higher in the aerobic dancers, with a standard deviation of 4.5.If this is a fair estimate of the data to be expected, how many women must she test in each group to produce a power coefficient of .90 at =.05?

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