**Please how how to do by hand. 2) Length of Theater Previews . Customers arrive at a movie theatre at the advertised movie time only to find that they have to sit through several previews and...

**Please how how to do by hand.

2) Length of Theater Previews. Customers arrive at a movie theatre at the advertised movie time only to find that they have to sit through several previews and pre-preview ads before the movie starts. Many complain that the time devoted to previews is too long (The Wall Street Journal, October 12, 2012). A preliminary sample conducted by
the Wall Street Journal
showed that the standard deviations of the amount of time devoted to previews was 4 minutes. Use that as a planning value for the standard deviation in answering the following questions.

1. If we want to estimate the population mean time for previews at movie theaters with a margin of error of 75 seconds, what sample size should be used? Assume 95% confidence.


2. If we want to estimate the population mean time for previews at movie theaters with a margin of error of 1 minute, what sample size should be used? Assume 95% confidence.