In Research on Cell Phone Use by Teenagers It Was $\alpha$

Multiple Choice

In research on cell phone use by teenagers it was found that the average connect 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 with a sample standard deviation of four minutes (assume a normal distribution) .What is the critical value for $\alpha$ = .001 to test the hypotheses.

A) 4.140
B) -4.140
C) 4.073
D) 3.291
E) 3.787