In 1990, the Average Duration of Long-Distance Telephone Calls Originating $9.4$

question 11

Multiple Choice

In 1990, the average duration of long-distance telephone calls originating in one town was $9.4$ minutes. A long-distance telephone company wants to perform a hypothesis test to determine whether the average duration of long-distance phone calls has changed from the 1990 mean of $9.4$ minutes. The mean duration for a random sample of 50 calls originating in the town was $8.6$ minutes. Does the data provide sufficient evidence to conclude that the mean call duration, $\mu$ , is different from the 1990 mean of $9.4$ minutes? Perform the appropriate hypothesis test using a significance level of $0.01$ . Assume that $\sigma=4.8$ minutes.

• A) With a \( z \) of \( -1.2 \) there is sufficient eridence to conclude that the mean value has changed from the 1990 mean of \( 9.4 \) minutes.
• B) With a P-value of \( 0.2302 \) there is not sufficient evidence to conclude that the mean value is less than the 1990 mean of \( 9.4 \) minutes.
• C) With a P-value of \( 0.2302 \) there is sufficient evidence to conclude that the mean value is less than the 1990 mean of \( 9.4 \) minutes.
• D) With a \( z \) of \( -1.2 \) there is not sufficient evidence to conclude that the mean value has changed from the 1990 mean of \( 9.4 \) minutes.

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Definitions:

Z-track

An injection technique designed to seal the medication in muscle tissue and prevent it from leaking into subcutaneous tissues.

Subcutaneous

Under the skin.

Inserting

This involves placing or fitting one object securely within another or a specific location, often used in surgical procedures or the administration of medical devices.

Sterile

Free from any form of bacteria, viruses, or other microorganisms, often referring to a condition necessary in medical procedures.