Airline Reservations Waiting Time: When customers phone an airline to make reser

Question

Airline Reservations Waiting Time: When customers phone an airline to make reservations, they usually find it irritating if they are kept on hold for a long time. In an effort to determine how long phone customers are kept on hold, one airline took a preliminary random sample of 167 phone calls and determined the average length of time (in minutes each caller was kept on hold). The sample standard deviation was 3.8 minutes. To estimate the true population mean hold times, the researcher wants to use a 96% confidence level. What is the critical value for the 96% confidence level? How many more customers should be included in the sample in order to be 96% sure that the sample mean of holding times is within one-half of a minute of the population mean hold times? How many more customers should be in the sample in order to be 96% sure that the sample mean of holding times is within 15 seconds of the population mean hold times?

Explanation / Answer

a. The critical Z for alpha=0.04 is 1.75.

b. n=[(zalpha/2*sigma)/E]^2, where, z denotes z critical at alpha/2, sigma is population standard deviation, and E is margin of error.

=[(1.75*3.8)/1.5]^2

=19.66~20 (ans)

c. n'=[(1.75*3.8)/0.25]^2

=707.56~708 (ans)

Related Questions

Navigate

• Browse (All)
• Browse A
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.