TABLE 10-14
a Problem with a Telephone Line That Prevents $$\text { t-Test: Two- Sample Assuming Unequal Variances }$$

question 152

Short Answer

TABLE 10-14
A problem with a telephone line that prevents a customer from receiving or making calls is disconcerting to both the customer and the telephone company. The data on samples of 20 problems reported to two different offices of a telephone company and the time to clear these problems (in minutes) from the customers' lines are collected. Below is the Excel output to see whether there is evidence of a difference in the mean waiting time between the two offices assuming that the
population variances in the two offices are not equal.
$$\text { t-Test: Two- Sample Assuming Unequal Variances }$$
$$\begin{array} { l r r } & \text { Office 1 } & \text { Office 2 } \\\hline \text { Mean } & 2214 & 2.0115 \\\text { Variance } & 2.951657 & 3.57855 \\\text { Observations } & 20 & 20 \\\text { Hypothesized Mean Difference } & 0 & \\\mathrm { df } & 38 & \\\mathrm { t } \text { Stat } & 0.354386 & \\\mathrm { P } ( \mathrm { T } < = \mathrm { t } ) \text { one- tail } & 0.362504 & \\\mathrm { t } \text { Critical one- tail } & 1.685953 & \\\mathrm { P } ( \mathrm { T } < = \mathrm { t } ) \text { two- tail } & 0.725009 & \\\mathrm { t } \text { Critical two-tail } & 2.024394 & \\\hline\end{array}$$

-Referring to Table 10-13, construct a 95% confidence interval estimate of the difference in proportion between the Kohler and Russell disks that are defective.

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Definitions:

Urinary Incontinence

The involuntary leakage of urine, indicating a loss of bladder control.

Indwelling Foley Catheter

A sterile tube inserted into the bladder to drain urine.

Urine Clots

Blood clots in the urine, which may be a sign of a medical condition affecting the kidneys, bladder, or urinary tract.

Cystitis

An inflammation of the bladder, often due to an infection, causing pain, urgent and frequent urination, and sometimes blood in the urine.