1.A sample of 80 Forbes magazine readers shows an average household income of 119 K and a standard deviation of 30k.

a.What would the 90% confidence interval be?_________________

b.Would the 95% confidence interval be narrower or wider?______

2.On a scale of 1-100, a sample of 10 restaurant guests showed a customer satisfaction level of 71 points and a standard deviation of 5 points.At 90%, what would be the confidence interval of the mean?

3.In a 2003, a preliminary study showed that 20% of Americans smoke. At 99% confidence, What would be an appropriate sample size to find out the proportion of American adults who smoke, if you want a margin of error of 2% _________

4.A study showed that 110 of 200 people say that their major source of news is TV.What would be a 90% confidence interval for the proportion? _____________