A Researcher Wanted to Determine If Using an Octane Booster $X _ { 1 }$

question 96

Multiple Choice

A researcher wanted to determine if using an octane booster would increase gasoline mileage. A random sample of seven cars was selected; the cars were driven for two weeks without the booster and two weeks with the booster. Use the definitions of $X _ { 1 }$ and $X _ { 2 }$ as given in the table. Consequently, $D = X _ { 1 } - X _ { 2 }$ .


Compute the standard deviation of the differences.

• A) 0.84
• B) 0.13
• C) 0.11
• D) 0.78

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