Confidence Intervals and Z-Scores

This video tutorial explains how to calculate a 95% confidence interval for an unknown population mean with a known population standard deviation. It covers the steps of recording given information, finding the Z-score, calculating the error bound, and constructing the confidence interval. The tutorial also demonstrates using technology to find the Z-score and concludes with interpreting the results.

What is the known population standard deviation in the given problem?

• 5 points

• 4 points

• 3 points

• 2 points

How many scores are in the random sample taken?

• 30

• 40

• 36

• 25

What is the confidence level used in this example?

• 90%

• 95%

• 99%

• 85%

What is the z-score corresponding to a 95% confidence level?

• 1.64

• 1.75

• 1.96

• 2.05

Which tool is NOT mentioned for finding the z-score?

• None of the above

• TI-84 Calculator

• Excel

• Desmos.com

What is the formula for calculating the error bound?

• Z-score plus sample mean

• Z-score times population standard deviation divided by square root of sample size

• Z-score divided by sample size

• Z-score times population standard deviation

What is the calculated error bound in this example?

• 0.98

• 1.05

• 1.02

• 0.95

What is the lower limit of the confidence interval?

• 69.02

• 66.02

• 67.02

• 68.02

What is the upper limit of the confidence interval?

• 67.98

• 70.98

• 68.98

• 69.98

What does the confidence interval estimate about the true population mean?

• It is exactly 68

• It is between 67.02 and 68.98

• It is less than 67

• It is more than 69