In research on cell phone use by teenagers it was found that the average time for a call was at least 15 minutes. Social psychologists feel that this study understated the time. To determine this claim, cell phone bills for 15 teenagers were evaluated. On average, the time spent was 18.5 minutes per call with a sample standard deviation of four minutes (assume a normal distribution).
-The appropriate test statistic to test the hypotheses is _____.
A)3.39
B)13.125
C)0.875
D)-0.875
E)-3.39

Question

Quizplus · Accepted Answer

The appropriate test statistic is calculated using the formula for a one-sample t-test: $t = \frac{\bar{x} - \mu}{(s/\sqrt{n})}$, where $\bar{x}$ is the sample mean, $\mu$ is the population mean under the null hypothesis, $s$ is the sample standard deviation, and $n$ is the sample size. Here, $\bar{x} = 18.5$, $\mu = 15$, $s = 4$, and $n = 15$. Plugging these values into the formula gives $t = \frac{18.5 - 15}{(4/\sqrt{15})} = 3.39$.

In Research on Cell Phone Use by Teenagers It Was