Question

A problem with a phone line that prevents a customer from receiving or making calls is upsetting to both the customer and the telecommunications company. Table 4 contains samples of 20 problems reported to two different offices of a telecommunications company and the time to clear these problems (in minutes) from the customers’ lines:  

Central Office I Time to Clear Problems (minutes): 1.48 1.75 0.78 2.85 0.52 1.60 4.15 3.97 1.48 3.10 1.02 0.53 0.93 1.60 0.80 1.05 6.32 3.93 5.45 0.97  

Central Office II Time to Clear Problems (minutes): 7.55 3.75 0.10 1.10 0.60 0.52 3.30 2.10 0.58 4.02 3.75 0.65 1.92 0.60 1.53 4.23 0.08 1.48 1.65 0.72

Is there evidence that Central Office II has made an improvement by reducing the mean waiting time from Office I? (Use alpha = 0.05.)

What is the alternative hypothesis for the variance test?

2. Referring to Table 4, what is the test statistic for the variance test?

3. Referring to Table 4, what is the p-value for the mean test?

4. Referring to Table 4, what is the critical value for the mean test?

5.  Referring to Table 4, what is the decision for the mean test?

6. referring to Table 4, what is the lower limit of a 95% confidence interval?

Answer 1

The test statistic is calculated using the formula mentioned. The p value and the critical value is obtained from STATKEY (image attached for reference). We compare the test statistic with the critical value and make the required decision. The lower limit 95% C.I is calculated using the formula mentioned.