In analyzing the city and highway fuel efficiencies of many cars and trucks, the

Question

In analyzing the city and highway fuel efficiencies of many cars and trucks, the mean difference in fuel efficiencies for the 642 vehicles was 7.45 mpg with a standard deviation of 2.46 mpg. Find a 95% confidence interval for this difference and interpret it in context. The 95% confidence interval for the difference in fuel efficiencies is 0 (Round to two decimal places as needed.) mpg nterpret this interval in context. Choose the correct answer below A. B. C D. There is a 95% chance that this interval captures the improvement in highway gas mileage compared to city gas mileage of the sample. About 95% of all samples will have a mean that falls within this interval One can have 95% confidence that this interval captures the true improvement in highway gas rileage compared to city gas mileage The true improvement in highway gas mileage compared to city gas mileage falls in this interval 95% of the time.

Explanation / Answer

The statistical software output for this problem is:

One sample T summary confidence interval:
: Mean of population

95% confidence interval results:

Hence,

95% confidence interval: (7.26, 7.64) mpg

Interpretation: Option C is correct.

Mean Sample Mean Std. Err. DF L. Limit U. Limit 7.45 0.097088456 641 7.2593501 7.6406499

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