In baseball, the American League allows a designated hitter (DH) to bat for the pitcher, who is typically a weak hitter. In the National League, the pitcher must bat. The common belief is that this results in American League teams scoring more runs. In interleague play, when American League teams visit National League teams, the American League pitcher must bat. So, if the DH does result in more runs, we would expect that American League teams will score fewer runs when visiting National League parks. To test this claim, a random sample of runs scored by American League teams without their DH is given in the following table and with their DH in the table on the following page. Does the designated hitter result in more runs scored at the α = 0.05 level of signiﬁcance?
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