Advertisers fear that users of DVRs (digital video recorders) will “fast forward” past commercials when they watch a recorded program. A leading British pay television company told its advertisers that this effect might be offset because DVR users watch more TV. A sample of 15 DVR users showed a daily mean screen time of 2 hours and 26 minutes with a standard deviation of 14 minutes, compared with a daily mean of 2 hours and 7 minutes with a standard deviation of 12 minutes for a sample of 15 non-DVR users.

(a-1) Construct a 95 percent confidence interval for the difference in mean TV watching.

The 95% confidence interval is from _______to________ .

(a-2) Would this sample support the company’s claim (i.e., is zero within the confidence interval for the mean difference)?

Yes

No

(b) State any assumptions that are needed.

The variances are equal.

The variances are unequal.