Please use ONLY one Excel file to complete the case study and upload the Excel file to the

submission link (Week 3 Case Study) for grading. Please clearly mark your answers

(either highlight or font colors) and grammar counts.

No credit will be granted for problems that are not completed using Excel.

In 2011, when the Gallup organization polled investors, 34% rated gold the best long-term

investment. In April of 2013 Gallup surveyed a random sample of U.S. adults. Respondents

were asked to select the best long-term investment from a list of possibilities. Only 241 of the

1005 respondents chose gold as the best long-term investment. By contrast, only 91 chose

bonds.

a. Compute the standard error for each sample proportion. Compute and describe a 95%

confidence interval in the context of the question.

b. Do you think opinions about the value of gold as a long-term investment have really

changed from the old 34% favorability rate, or do you think this is just sample

variability? Explain.

c. Suppose we want to increase the margin of error to 3%, what is the necessary sample

size?

d. Based on the sample size obtained in part c, suppose 120 respondents chose gold as the

best long-term investment. Compute the standard error for choosing gold as the best

long-term investment. Compute and describe a 95% confidence interval in the context of

the question.

e. Based on the results of part d, do you think opinions about the value of gold as a long-

term investment have really changed from the old 34% favorability rate, or do you think

this is just sample variability? Explain.