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Part I.
[Use the MPG data that you used for Assignment #2.]
a.
Summarize your model selection.
We chose to use a twosample pooled variance with t because we have two samples,
one for midsize cars and one for SUV’s and because we do not know the population
variances.
. We assumed that the samples are independent random samples. We used a
QQ normal plot to determine that both the sample of midsize cars and SUV’s are
approximately normal. Based on the results from the Stat Tools OneVariable
Summary, we concluded that the variance of midsize cars is equal to the variance of
SUV’s because the larger variance, 8.655, is not twice as large as the smaller
variance, 8.258.
QQ Normal Plot of MPG / Midsize Cars
3.5
2.5
1.5
0.5
0.5
1.5
2.5
3.5
3.5
2.5
1.5
0.5
0.5
1.5
2.5
3.5
ZValue
Standardized QValue
QQ Normal Plot of MPG / SUV's
3.5
2.5
1.5
0.5
0.5
1.5
2.5
3.5
3.5
2.5
1.5
0.5
0.5
1.5
2.5
3.5
ZValue
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View Full Document MPG (Midsize)
MPG (SUV)
One Variable Summary
Data Set #1
Data Set #1
Mean
26.750
20.105
Variance
8.258
8.655
Std. Dev.
2.874
2.942
Skewness
0.3632
0.8213
Kurtosis
2.2311
3.5584
Median
26.000
19.000
Mean Abs. Dev.
2.438
2.249
Minimum
22.000
15.000
Maximum
33.000
27.000
Range
11.000
12.000
Count
32
19
Sum
856.000
382.000
1st Quartile
24.000
18.000
3rd Quartile
28.000
22.000
Interquartile Range
4.000
4.000
b.
Determine the 95% confidence interval to estimate the difference in mean miles per
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This note was uploaded on 02/16/2010 for the course BUS MGT 330 taught by Professor Schroeder during the Winter '08 term at Ohio State.
 Winter '08
 SCHROEDER

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