At one school,the average amount of time that $\text { tenth-graders }$ spend watching television each week is $21.6 \text { hours. }$ The principal introduces a campaign to encourage the students to watch less television.One year later,the principal wants to perform a hypothesis test to determine whether the average amount of time spent watching television per week has decreased from the previous mean of $21.6 \text { hours. }$

Question

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Since the principal aimed to reduce the average amount of time the students spend watching television, they are expecting the mean to decrease rather than increase or change in both directions. Therefore, we need to perform a one-tailed test in the direction of the expected change, which is in this case, a decrease. A lower-tailed test is used to test the hypothesis that the true population mean is less than the previous mean of 11ea9518_d5af_4a52_9016_d780a76a4be4_TB3450_11.

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