The mean and standard deviation of a random sample of n measurements are equal to 34.4 and 3.6​, respectively. a. Find a 90​% confidence interval for μ if n=64. b. Find a 90​% confidence interval for μ if n=256. c. Find the widths of the confidence intervals found in parts a and b. What is the effect on the width of a confidence interval of quadrupling the sample size while holding the confidence coefficient​ fixed?

1 h 4. A fashion designer wants to know how many new dresses women buy each year. A sample of 650 women was taken to study their purchasing habits. Construct the 95% confidence interval for the mean number of dresses purchased each year if the sample mean was found to be 5.6. Assume that the population standard deviation is 1.3. Round your answers to one decimal place. Answer: Lower endpoint: Upper endpoint: iny ir

Let μ denote some population mean of interest and suppose a 95% confidence interval for μ is calculated to be (0.63, 0.73) and a 99% confidence interval for μ is calculated to be (0.61,0.75). Also, suppose that we want to test H0: μ = 0.74 vs. Ha: μ ≠ 0.74 What can you say about the corresponding p-value? Choose from following letters.  a. The corresponding p-value will be smaller than 0.05 but larger than 0.01. b. The corresponding p-value will be larger than 0.05. c. I can’t say anything about the corresponding p-value until I run the test.

A simple random sample of size n is drawn from a population that is normally distributed. The sample mean, x, is found to be 19.1, and the sample standard deviation, s, is found to be 4.9. (a) Construct a 96% confidence interval about u if the sample size, n, is 39. (b) Construct a 96% confidence interval about u if the sample size, n, is 68. How does increasing the sample size affect the margin of error, E? (c) Construct a 98% confidence interval about u if the sample size, n, is 39. How does increasing the level of confidence affect the size of the margin of error, E? (d) If the sample size is 14, what conditions must be satisfied to compute the confidence interval? (a) Construct a 96% confidence interval about u if the sample size, n, is 39. Lower bound: Upper bound: (Round to two decimal places as needed.) (b) Construct a 96% confidence interval about u if the sample size, n, is 68. Lower bound: Upper bound: (Round to two decimal places as needed.) How does increasing the sample…