Fry Brothers heating and Air Conditioning, Inc. employs Larry Clark and George Murnen to make service calls to repair furnaces and air conditioning units in homes. Tom Fry, the owner, would like to know whether there is a difference in the mean number of service calls they make per day. Assume the population standard deviation for Larry Clark is 1.05 calls per day and 1.23 calls per day for George Murnen. A random sample of 40 days last year showed that Larry Clark made an average of 4.77 calls per day. For a sample of 50 days George Murnen made an average of 5.02 calls per day. At the .05 significance level, is there a difference in the mean number of calls per day between the two employees? What is the p-value?
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Hypothesis Test: Independent Groups (t-test, pooled variance)
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Larry
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George
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4.77
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5.02
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mean
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1.05
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1.23
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std. dev.
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40
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50
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n
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88
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df
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-0.25
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difference (Larry - George)
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1.33102
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pooled variance
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1.1537
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pooled std. dev.
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0.24474
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standard error of difference
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0
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hypothesized difference
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-1.02
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t
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0.3098
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p-value (two-tailed)
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-0.73636
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confidence interval 95.% lower
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0.23636
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confidence interval 95.% upper
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0.48636
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margin of error
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