Confidence Intervals and Z-Scores

The video tutorial explains how to construct a 90% confidence interval for a population proportion. It uses a class project example where a political science student surveys 500 students to estimate the percentage of registered voters. The tutorial covers calculating the sample proportion, determining the confidence level and alpha, finding the z-score, and computing the error bound. Finally, it demonstrates how to calculate the confidence interval, estimating that 56.4% to 63.6% of students are registered voters.

What is the main objective of the political science student's class project?

• To determine the average age of students

• To find out the number of students who own a car

• To estimate the percentage of students who are registered voters

• To calculate the average GPA of students

How is the sample proportion (p') calculated in this example?

• By dividing the number of registered voters by the total number of students surveyed

• By subtracting the number of non-registered voters from the total number of students

• By multiplying the number of registered voters by the total number of students

• By adding the number of registered and non-registered voters

What is the value of q' if p' is 0.6?

• 0.3

• 0.5

• 0.6

• 0.4

What is the alpha value when the confidence level is 90%?

• 0.05

• 0.1

• 0.9

• 0.01

Which tool is used to verify the z-score in this example?

• Python script

• Excel spreadsheet

• R programming

• TI-84 calculator

What is the approximate z-score for a 90% confidence level?

• 2.33

• 1.645

• 1.96

• 1.28

How is the error bound calculated in this example?

• By dividing the z-score by the sample standard deviation

• By adding the z-score to the sample proportion

• By multiplying the z-score by the sample standard deviation for the proportion

• By subtracting the z-score from the sample proportion

What is the margin of error to three decimal places?

• 0.045

• 0.036

• 0.065

• 0.056

What is the lower bound of the 90% confidence interval?

• 0.564

• 0.536

• 0.636

• 0.600

What does the confidence interval suggest about the percentage of registered voters?

• It is between 56.4% and 63.6%

• It is less than 50%

• It is more than 70%

• It is exactly 60%