Statistics Final Exam - Speech or Presentation Example

In the case of work completed in Excel, copy and paste show the formula(s) used. No work = no credit. The problems on this exam pertain to the Malls of the Thump McDonald Property group. Thump McDonald, often referred to as “The McDonald”, commissioned his apprentices to look at various statistics to determine the efficiency of his operations. A supplier manufactures batteries for the emergency backup lights in the mall corridors. A random sample of 256 batteries is taken and the sample mean life is 6.

5 years with a standard deviation of 0.65 years. The law requires 99% confidence of operation when scheduling of battery replacement. Mall security estimates that the average daily per-store theft is exactly $335, but wants to determine the accuracy of this statistic. The company researcher takes a sample of 81 clerks and finds that =$300 and s = $80. A confidence interval of 90% was used to estimate the proportion of customers who buy at least two items during their shopping mall experience.

A random sample of 150 customers produced the following confidence interval: 32% +/- 4%. What is the best way to explain the results? z-test should be used when the sample size is greater than 30 (n>30) and when the mean and the standard deviation are known. T-test is best suites when the sample size is lesser than 30 (n