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Unit 4 Complete

For the Week 4 Complete assignment, solve each problem and answer each question that corresponds with it. Explain how you arrived at the answer for each problem. The total word count for your assignment should be a minimum of 1200 words with three scholarly sources one of which may include -Textbook(s)

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Donnelly, R. A. (2020). Business statistics (3rd ed.). Pearson.

Special Note: Keep in mind the word count does not count the words currently on this document which is 557.

1. The following data show the costs charged by a tax preparation service for a random sample of 15 tax returns.  Table  Description automatically generated

     a. Using a 98% confidence interval, estimate the average cost of the service for preparing a tax return for a customer.       b. What is the margin of error for this sample?       c. Verify your result using Excel.       d. What assumptions are necessary for this analysis?

Student Response (Reminder: References go on the reference page at the end of the document.

2. The makers of compact fluorescent light bulbs (CFL) claim the bulbs use 75% less energy and last 10 times longer than incandescent bulbs. A 16-watt CFL (equivalent to a 60-watt incandescent) has a rated lifetime of 8,000 hours. To test this claim, a random sample of 50 CFLs was drawn, and the average life of a bulb was determined to be 7,960 hours. Assume the standard deviation for the life of CFL bulbs is 240 hours.       a. Does this sample provide enough evidence to support the claim that CFLs average 8,000 hours with 95% confidence?       b. What is the margin of error for this sample using a 95% confidence interval?       c. Verify your result using Excel.

Student Response (Reminder: References go on the reference page at the end of the document.

3. Certain advertisers would like to estimate the proportion of viewers who spend the majority of their television time watching alone. The consensus is that this percentage has been increasing over the years due to the increased number of television sets in U.S. households.       a. Determine the sample size needed to construct a 90% confidence interval with a margin of error no more than 5% to estimate the true proportion of viewers who watch television alone.       b. What impact would a pilot sample that showed that 38% of viewers spend the majority of their television time watching alone have on your results?

Student Response (Reminder: References go on the reference page at the end of the document.

4. To design a new advertising campaign, Volkswagen would like to estimate the proportion of drivers of the new VW Beetle who are women. In a random sample of 250 Beetle owners, 140 of them were women.       a. Construct a 95% confidence interval to estimate this proportion.       b. What is the margin of error for this sample?

Student Response (Reminder: References go on the reference page at the end of the document.

5. Verizon Wireless would like to estimate the average number of text messages received by American teenagers per month. A random sample of 60 teenaged customers was selected. The sample average was 2,272 messages per month, and the sample standard deviation was 953 messages per month. Construct confidence intervals with the following confidence levels:       a. 90%       b. 95%       c. 99%

Student Response (Reminder: References go on the reference page at the end of the document.

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