The following are true about confidence intervals: a. they indicate the presence or otherwise of a statistical difference between two populations b. the intervals are larger with smaller sample size c. the intervals give a range of values within which the true value will lie. d. a 95% confidence interval means that 95% of all observed values fall within that interval. e. None of the above.

tion. Use this information to construct the 90% and 95% confidence intervals fc of the confidence intervals. ce of a certain stock was $123.13. Assume the population standard deviation is

Next question If a sample proportion is 0.68, which of the following could be a 90% confidence interval for the population proportion? ..... Select all that apply. A. Lower bound: 0.59; Upper bound: 0.77 B. Lower bound: 0.66; Upper bound: 0.70 OC. Lower bound: 0.50; Upper bound: 0.77 D. Lower bound: 0.77; Upper bound: 0.95 E. Lower bound: 0.67; Upper bound: 0.71 F3 F4 F5 F7 F8 24 4. %23 2 3. 6. Left control option command

At a charter high school, the average GPA of a high school senior is known to be normally distributed. After a sample of 27 seniors is taken, the average GPA is found to be 2.85 and the sample variance is determined to be 0.16. Find a 95% confidence interval for the population mean GPA.   a. 2.5615 to 2.8585 b. 2.6358 to 3.0642 c. 2.6917 to 3.0083 d. 2.5167 to 2.9033

Suppose a researcher takes a random sample of 1,000 students from a university and creates a 95% confidence interval for the true proportion of left handed students at the university. Which of the following is true about this interval when compared with a 95% confidence interval based on a random sample of 600 students from the same university? a. The interval based on a sample of 600 students will be wider than the interval based on a sample of 1,000 students. b. The lower and upper endpoints of the 95% CI based on 600 students will both be larger than the corresponding lower and upper endpoints of the 95% CI based on 1,000 students. c. 95% CIs based in samples of 1,000 students are more likely to include the true population proportion than 95% CIs based on samples of 600 students. d. The interval based on a 1,000 students will be wider than the interval based on 600 students.   2. If the researchers above wished to decrease the width of the mean confidence interval for the mean age…

The following questions are concerned with confidence interval estimation of one population mean. (true or false) a. The margin of error can be determined if one knows only the length of the confidence interval b. The confidence interval can be obtained if one knows the margin of error and the sample mean c. The sample mean can be determined if one knows the endpoints of the confidence interval