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).
-How much evidence do we have that cell phone conversations are longer than the original claim?
A)No evidence
B)Some evidence
C)Strong evidence
D)Very strong evidence
E)Extremely strong evidence

Question

Quizplus · Accepted Answer

To determine the evidence supporting the claim that cell phone conversations are longer than the original claim of 15 minutes, a hypothesis test can be conducted. The null hypothesis (H0) would state that the average call duration is 15 minutes, while the alternative hypothesis (H1) would suggest that the average call duration is greater than 15 minutes. Given the sample mean of 18.5 minutes, a sample standard deviation of 4 minutes, and a sample size of 15 teenagers, we can calculate the test statistic (usually a t-score for a sample of this size) and then determine the p-value associated with this test statistic. Without performing the exact calculations here, the fact that the sample mean (18.5 minutes) is significantly higher than the hypothesized mean (15 minutes), with a relatively small standard deviation and a decent sample size, suggests that there is very strong evidence against the null hypothesis. This indicates that the average call duration is indeed longer than 15 minutes, thus providing very strong evidence supporting the social psychologists' claim.

In Research on Cell Phone Use by Teenagers It Was