**1. **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

**5.** A sample of 163 randomly selected students, found that the proportion of students planning to travel home for thanksgiving is 0.72. What is the standard deviation of the sampling distribution?

**6. **A survey of 422 citizen found that 353 of them favor a new bill introduced by the city. We want to find a 95% confidence interval for the true proportion of the population who favor the bill. What is the lower limit of the interval? (Round to 3 decimal digits).

**7.** Compute a 95% confidence interval for the population mean, based on the sample numbers 21, 28, 33, 34, 25, 26, and 135. Which table do we use to find the margin of error?

**8.** Compute a 95% confidence interval for the population mean, based on the sample 21, 28, 33, 34, 25, 26, and 135. What is the critical value, (4 decimal digits)

**9.** Compute a 95% confidence interval for the population mean, based on the sample numbers 21, 28, 33, 34, 25, 26, and 135. What is the margin of error? (2 decimal digits)