Question

1. 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.

   Miles / Gal Without	Miles / Gal With
   21.2	23.8
   25.4	25.6
   20.9	22.4
   27.6	28.3
   22.8	24.5
   27.3	28.8
   23.4	25.2

A) 0.78

B) 0.69

C) 0.87

D) 0.48

Answer 1

This is asking for standard deviation of paired differences.

Statistics software output:

Hence, answer is Option A) 0.78

If it is asking something else please post in comment I will answer. Thank you.