Question

From her firm's computer telephone log, an executive found that the mean length of 69 telephone calls during July was 4.91 minutes with a standard deviation of 5.93 minutes. She vowed to make an effort to reduce the length of calls. The August phone log showed 47 telephone calls whose mean was 2.868 minutes with a standard deviation of 2.840 minutes. Steps: 1. Open Minitab on your computer. 2. There is no data file for this example. The information above contains summarized data (take info from story and plug into Minitab)

(a)	Obtain a test statistic tcalc and p-value assuming unequal variances. (Use Minitab. Round your answers to 3 decimal places.)

tcalc
p-value

Interpret the results using α = .01.

(Click to select) Do not reject/Reject the null hypothesis.

What is your conclusion at α = .01?

  

We (Click to select) cannot/can conclude the length of calls had been reduced.

Answer 1

————— 7/28/2019 8:46:19 PM ————————————————————

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Two-Sample T-Test and CI

Sample N Mean StDev SE Mean
1 69 4.91 5.93 0.71
2 47 2.87 2.84 0.41

Difference = μ (1) - μ (2)
Estimate for difference: 2.042
99% lower bound for difference: 0.092
T-Test of difference = 0 (vs >): T-Value = 2.47 P-Value = 0.007 DF = 104

From the table we see that, Test statistic value tcalc = 2.47, P-value = 0.007

and we also see that, P-value = 0.007 < = 0.01 Hence, we reject the null hypothesis.

Conclusion:- We can conclude that length of calls had been reduced.