Question

3. Of the following characteristics, the t-distribution and z-distribution are the same in all but one. Which one is it?

Multiple Choice

• Continuous

• Bell-shaped

• Symmetrical

• Mean = 0, and standard deviation = 1

4. A university surveyed recent graduates of the English department for their starting salaries. Four hundred graduates returned the survey. The average salary was $25,000. The population standard deviation was $2,500. What is the 95% confidence interval for the mean salary of all graduates from the English department?

Multiple Choice

• [$24,988, $25,012]

• [$24,600, $25,600]

• [$24,755, $25,245]

• [$22,500, $27,500]

5. A group of statistics students decided to conduct a survey at their university to find the average (mean) amount of time students spent studying per week. Assuming a population standard deviation of six hours, what is the required sample size if the error should be less than a half hour with a 95% level of confidence?

Multiple Choice

• 130

• 554

• 35

• 393

6. The distribution of Student's t is ________.

Multiple Choice

• a discrete probability distribution

• symmetrical

• positively skewed

• negatively skewed

7. When we use a confidence interval to reach a conclusion about the population mean, we are applying a type of reasoning or logic called __________.

Multiple Choice

• the normal distribution

• statistical inference

• descriptive statistics

• graphics

8. A survey of an urban university (population of 25,450) showed that 870 of 1,100 students sampled supported a fee increase to fund improvements to the student recreation center. Using the 95% level of confidence, what is the confidence interval for the proportion of students supporting the fee increase?

Multiple Choice

• [0.767, 0.815]

• [0.759, 0.822]

• [0.714, 0.866]

• [0.771, 0.811]

9. A research firm needs to estimate within 3% the proportion of junior executives leaving large manufacturing companies within three years. A 0.95 degree of confidence is to be used. Several years ago, a study revealed that 21% of junior executives left their company within three years. To update this study, how many junior executives should be surveyed?

Multiple Choice

• 709

• 594

• 897

• 612

Answer 1