MATH 160 CMU Estimating a Population Proportion & Confidence Interval Worksheet

Progress Check

Use this activity to assess whether you and your peers can:

• Calculate a 90% and a 95% confidence interval.
• Relate the interval width of a confidence interval to its margin of error (MOE).
• Compare interval widths of two confidence intervals and draw conclusions.

Learn by Doing

Use the rubric at the bottom of this page as a guide for completing this assignment.

Directions

Submit your work:

• Commit a good-faith effort to address all items in the Prompt section below. Please be sure to number your responses.

Complete your assigned peer reviews:

• After you submit your initial good-faith attempt, continue to the ANSWER(S) page and review your instructor’s response. But please do not submit your corrected work yet.
• Within three days after the due date, return to this assignment and complete your assigned peer reviews (directions (Links to an external site.)).

Submit your corrected work:

• We all learn from mistakes (our own and our classmates’ mistakes). So please do not immediately correct your own mistakes. If possible, wait until you receive feedback from at least one of your peers.
• If necessary, correct your work and resubmit the entire assignment. Your instructor will only review and grade your most recent submission, so please do not refer to a previous submission.

Prompt

Harris Interactive® conducted a poll of American adults in August of 2011 to study the use of online medical information. Of the 1,019 randomly chosen adults, 60% had used the Internet within the past month to obtain medical information.

1. Use the results of this survey to create an approximate 95% confidence interval estimate for the percentage of all American adults who have used the Internet to obtain medical information in the past month.
2. Calculate the 90% confidence interval.
3. Which confidence interval has the smaller margin of error? Why does this make sense?
4. Which confidence interval is more likely to contain the true percentage of all American adults who have used the Internet to obtain medical information in the past month? Why do you think so?

Rubric