An air-conditioning supplier uses two installers. He is interested in comparing the time each installer takes...

An air-conditioning supplier uses two installers. He is interested in comparing the time each installer takes to install an air-conditioning unit. Data concerning installation times was collected over a period of time, and the following results were determined. (Note: the installation times are in hours).

	Sample Mean	Sample Standard Deviation	Sample Size
Installer A	3	1.1952	8
Installer B	4	1.4142	7

Is there evidence, at the 5% level of significance, of a difference in the average time of installation between the two installers? (You may assume that all installation times are normally distributed, and Installer A and Installer B have equal population variances). You may use the following Excel output.

t-Test: Two-Sample Assuming Equal Variances

	Installer A	Installer B
Mean	3	4
Variance	1.429	2.000
Observations	8	7
Pooled Variance	1.692
Hypothesized Mean Difference	0
df	13
t Stat	-1.485
P(T<=t) one-tail	0.081
t Critical one-tail	1.771
P(T<=t) two-tail	0.161
t Critical two-tail	2.160

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orchestra answered 1 year ago

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