11. Describe the effect that an increase in each of the following has on the width of a confidence interval: a. The lever of confidence (while holding the sample size and standard deviation constant). b. The sample size (while holding the confidence level and standard deviation constant). c. The standard deviation (while holding the sample size and confidence level constant).

Tina catches a 14-pound bass.  She does not know the population mean or standard deviation.  So she takes a sample of five friends and they say the last bass they caught was 9, 12, 13, 10, and 10 pounds.  Find the t and calculate a 95% (α = .05) confidence interval.

In a survey, 28 people were asked how much they spent on their child's last birthday gift. The results were roughly bell-shaped with a mean of $45 and standard deviation of $14. Construct a confidence interval at a 99% confidence level. Give your answers to one decimal place. ________+________

Look at the picture

A professor was curious about her students' grade point averages. She took a random sample of 15 students and found a mean GPA of 3.01 with a standard deviation of 0.534. Which of the following formulas gives a 99% confidence interval for the mean GPA of the professor's students?

The accompanying table shows data for the weights of backpacks for men and women. Assume that the data are from random samples and the distributions are Normal. Complete parts (a) and (b) below. E Click the icon to view the data table. a. Find a 95% confidence interval for the difference between means HFemale - HMale state whether it captures 0, and explain what that shows about the mean. The 95% confidence interval is ( D (Round to two decimal places as needed. Use ascending order.) Backpack weights Female Male 10 10 12 8 9. 7 5 10 7 20 3 11 8 14 13 11 14 6 7 22 11 12 15 10 17 22 10 7 25 11 7 15 11 11 4 16 13 20 21 15 10 9. 16 10 15 13 10 10 17 12 11 38 6. 6. 7 19 12 13 20 8 14 15 18 19 10 16 16 13 18 12 14 13 13 15 14 14 7 7 14 13 27 11

Which type of confidence interval should you use in this situation? A sample of 25 different payroll departments found that the employees worked an average of 310.3 days a year with a standard deviation of 23.8 days. The distribution is approximately normally distributed. Find the 90% confidence interval for the average days worked of all payroll departments.   Question 2 options:   1)  a confidence interval for the mean using a table value from the standard normal distribution.   2)  a confidence interval for the mean using a table value from the t distribution.   3)  a confidence interval for a proportion using a table value from the standard normal distribution.   4)  a confidence interval for proportion using a table value from the t distribution.   5)  none of the above.

If the analyst decides to increase the sample size (n) from 75 to 100, while maintaining the same confidence level, the width of the confidence interval would then: fluctuate up and down. remain unchanged. decrease. increase.