1. Excel Assignment

Please submit your Excel file and highlight your answers in color.

Brief Case

Has Gold Lost its Luster? In 2011, when the Gallup organization polled investors, 34% rated gold the best long-term investment. However, 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.

• With 95% confidence, compute the margin of error of the sample proportion.
• Compute and describe a 95% confidence interval in the context of the case.
• Do you think opinions about the value of gold as a long-term investment have really changed from the old 34% favorable rate, or do you think this is a sample variability? Explain your answer using the calculated statistics.
• Suppose the Gallup organization wants to offer a new investment option and wants to estimate, to within 5%, the proportion of customers who are likely to make this new investment with 95% confidence. How large a sample do they need?

2. Excel Assignment

Samsung manufactures cellphone with an average standby time of 10 hours between charges. The standby time of the cellphone is normally distributed. During the design stage, the quality engineering staff recorded 18 observations of the standby time of the cellphone. Using the observations below, is there evidence that the average standby time of a Samsung cellphones is not 10 hours? Use a level of significance of .05

Observation

Observations	Time
1	10.85
2	11.4
3	10.81
4	10.24
5	10.23
6	9.49
7	9.89
8	10.11
9	10.57
10	11.21
11	10.1
12	11.22
13	10.31
14	11.24
15	9.51
16	10.52
17	9.92
18	8.33

Answer the following question:

1. What is the null and alternative hypothesis to the case above?
2. Copy the data into excel and do an analysis to test the hypothesis

3. What is the conclusion of your analysis? (try to state it in terms of the original problem or question)

4. Develop the 95% confidence interval.