Confidence Interval WS

Confidence Intervals

[WLO: 2] [CLOs: 1, 3]

Prior to beginning work on this assignment, read Chapter 8: Confidence Interval Estimations.

You may find it helpful to review Excel Tutorial - Calculating Confidence Intervals (Links to an external site.) and How to Calculate Confidence Intervals in Excel (Links to an external site.).

In this week’s reading, the text discussed different types of samples and their distributions, and sampling errors, probabilities, and confidence intervals. Using Excel, complete the problem below. This is similar to Problem 33 in Chapter 8.

Problem: You have been assigned to determine whether more people prefer Coke or Pepsi. Assume that roughly half the population prefers Coke and half prefers Pepsi. How large a sample do you need to take to ensure that you can estimate, with 90% confidence, the proportion of people preferring Coke to within 5% of the actual value? Show all of your work.

In your Excel spreadsheet,

• Identify the sample size.
• Utilize the support tool of Excel.
• Present any equations utilized.