9.13 Advertising at the Movies "Welcome to the new movie pre-show!" Before you can see the newly released movie you have just paid to see, you must sit through a variety of trivia slides, snack bar ads, paid product advertising, and movie trailers. Although the total barrage of advertising may last up to 20 minutes or more, a particular theatre chain claims that the aver- age length of any one advertisement is no more than 3 minutes. To test this claim, 50 theatre advertise- ments were randomly selected and found to have an average duration of 3 minutes 15 seconds with a stan- dard deviation of 30 seconds. Do the data provide sufficient evidence to indicate that the average duration of theatre ads is more than that claimed by the theatre? Test at the 1% level of significance. (HINT: Change "seconds" to fractions of a "minute.")