In order to control costs, a company wishes to study the amountof money its sales force spends entertaining clients. The followingis a random sample of six entertainment expenses (dinner costs forfour people) from expense reports submitted by members of the salesforce
(a) Calculate x¯x¯ , s2,and s for the expense data. (Round "Mean" and"Variances" to 2 decimal places and "Standard Deviation" to 3decimal places.)
(b) Assuming that the distribution ofentertainment expenses is approximately normally distributed,calculate estimates of tolerance intervals containing 68.26percent, 95.44 percent, and 99.73 percent of all entertainmentexpenses by the sales force. (Round intermediatecalculations and final answers to 2 decimals.)
| |
| [x¯x¯ ± s] | [, ] |
| [x¯x¯ ± 2s] | [, ] |
| [x¯x¯ ± 3s] | [, ] |
|
(c) If a member of the sales force submits anentertainment expense (dinner cost for four) of $390, should thisexpense be considered unusually high (and possibly worthy ofinvestigation by the company)? Explain your answer.
(d) Compute and interpret the z-score for eachof the six entertainment expenses. (Round z-scorecalculations to 2 decimal places. Negative amounts should beindicated by a minus sign.)
