Asked Dec 9, 2019

Construct a 90% confidence interval for the mean highway mileage for hybrid cars. A random sample of 8 hybrid cars had the following highway mileages in mpg.
36 41 37 45 50 40 32 39


Expert Answer

Step 1


The sample mean is obtained below:

From the given information, number of observations is 8 and confidence level is 90%.

The required mean is,


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Σ п 36 + 41+..39 8. = 40

Step 2

The sample standard deviation is obtained below:


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E(x-x) п-1 (36 – 40) + (41– 40)° + .+ (39 – 40) 8 – 1 = 5.5549

Step 3

The critical value is obtained below:

The level of significance=1-0.90=0.10.

The degrees of freedom= 8-1=7

The critical value is,

From the EXCEL, using the formula, =T.INV.2T(0.10,7), the critical value is...

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