Question

4) In addition to studying the mean monthly sales of the product, the analyst wishes to study the proportion of stores that have experienced a return rate of at least 20% of the product sold at its store within 90 days of the purchase of the item. Store policy requires any return of the shirt to be done at the store at which the shirt was purchased. What minimum numbers of stores need to be selected to estimate the desired population proportion under the following conditions? Explain the meanings of the minimum sample sizes you compute. a) The estimate is desired to within ±10% with 99% confidence when the population proportion of stores that has experienced at least this return rate has been thought to equal 15%. b) The estimate is desired to within ±10% with 99% confidence when the population proportion of stores that has experienced at least this return rate is unknown. c) The estimate is desired to within ±10% with 99% confidence when the population proportion of stores that has experienced at least this return rate has been thought to equal 5%. Comment upon the changes in the minimum sample sizes you have computed based upon the changes in the information in the parts of this problem. Again, compare your answers to the answer of the first part of the problem only. Do not use only mathematical justifications to explain why there are differences in the results at which you arrived for the parts of the problem.

Answer 1