Androstenedione (andro) is a steroid that is thought by some athletes to increase strength. Researchers investigated this claim by giving andro to one group of men and a placebo to a control group of men. One of the variables measured in the experiment was the increase in "lat pull down" strength (in pounds) of each subject after 4 weeks. (A lat pull down is a type of weightlifting exercise.) The raw data are given below and are summarized in the table.

(a) Conduct a t test to compare the two groups at α = 0.10. Use a non directional alternative.
(b) Prior to the study it was expected that andro would increase strength, which means that a directional alternative might have been used. Redo the analysis in part (a) using the appropriate directional alternative.

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n Mean SD 9 14.4 13.3 Andro Control 10 20.012.5 Control Andro 30 10 10 30 40 20 30 20 10 40 20 10 10 0 0 10 0 10 30