The report of a sample survey of 1014 says with 95% confidence, between 9% and 15% of all Americans expect to spend more on gift this year than last year

2.What is the critical value of t for a 90% confidence interval with df-14? (Assume a 2-tail test)

3.What is the critical value of A 95% confidence interval based on a sample of 20? (Population standard deviation is unknown). Assume a 2tail test.

4.A survey of 30 random shoppers found a 95% confidence interval that shoppers will spend between $24.50 and 28.30. A second survey surveyed 25 random shoppers