A researcher is studying whether the average weekly time spent on social media by college students is different from the national average of 12 hours per week. A random sample of 30 college students is collected, yielding a sample mean of 13.2 hours and a sample standard deviation of 4.5 hours. Which formula should the researcher use to calculate the test statistic? $T = \frac{\bar{x} - \sigma}{s/\sqrt{n}}$ $Z = \frac{\bar{x} - \sigma}{s/\sqrt{n}}$ $T = \frac{\bar{x} - \mu}{s/\sqrt{n}}$ $Z = \frac{\bar{x} - \mu}{s/\sqrt{n}}$ $T = \frac{\bar{x} - \mu}{s/\sqrt{n}}$
Added by Samuel L.
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Since the population standard deviation is unknown, we should use a t-test. The null hypothesis is that the population mean is $\mu = 12$ hours. The sample mean is $\bar{x} = 13.2$ hours. The formula for the t-test statistic is given by: Show more…
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