stat 121 credit quiz 18 a-r

Suppose a 95% confidence interval was made to estimate the monthly cost of Internet service instead of a 90% confidence interval. Fill in the blank: The 95% confidence interval will be _______ the 90% confidence interval.

wider than

Proceed to the statistical inference. Using the sliding bar, calculate a 90% confidence interval to estimate the average weight of an NBA player.

(213.81, 214.49)

The average height of BYU freshman from a random sample of 450 freshman at BYU is 68 inches with a standard deviation of 1.5 inches. What is the 98% confidence interval for the average height of BYU freshman?

(67.83, 68.17)

What is the z* associated with 95% confidence?

1960

Regardless of confidence level, what will the center of our confidence interval be? (Hint: What is x-bar?)

214.15

Consider the following confidence interval interpretation: "We are 98% confident that the true mean laptop screen size is between 19.2 and 21.4 inches". Is this interpretation of a confidence interval correct or incorrect? Why or why n

Correct. It gives all three parts of confidence interval interpretation.

Consider the following confidence interval interpretation: "The mean of all laptop screen sizes lies between 12.47 and 15.59". Is this interpretation of a confidence interval correct or incorrect? Why or why not?

Incorrect. It does not give a level of confidence

Consider the following confidence interval interpretation: "We are 95% confident that we have found a confidence interval that contains the true mean number of Utah high school students involved in a car accident per month". Is this interpretation of a confidence interval correct or incorrect? Why or why not?

Incorrect. It does not state the actual confidence interval

To estimate the average time taken to complete the Stat 121 final exam, instructors randomly selected 150 students that had previously taken the course and recorded their time on the test. The instructors then calculated a 98% confidence interval to be (98, 142) minutes. What is the parameter the instructors are trying to estimate?

The mean time taken by all students on the Stat 121 final exam

Generate a histogram of the data. Is it appropriate to calculate a one-sample t confidence interval for means to estimate the average weight of an NBA player?

Yes, because the sample histogram appears to be normal.