An endocrinologist is interested in the effects of depression on the thyroid. It is believed that healthy subjects have a mean thyroxin level of 7.0 mcg/100ml and a standard deviation of 1.6mcg/100 ml. The endocrinologist wants to assess whether the mean thyroxin level is different for those with depression. She samples 35 subjects with depression and obtains a sample mean of 7.82 mcg/100 ml for thyroxin.

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