# The report of a sample survey of 1014 says with 95% confidence

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)

Here’s the SOLUTION

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