Scientists did a study to see whether a new fuel additive had any effect on gas mileage (mpg). Seven identical cars were driven for 1 week with normal gas/no additive, and then driven the next week...

Scientists did a study to see whether a new fuel additive had any effect on gas mileage (mpg). Seven identical cars were driven for 1 week with normal gas/no additive, and then driven the next week using gas with the additive. The miles-per-gallon was recorded for each vehicle. Please use the appropriate t-test and do the calculations requested below and fill in the blanks.

No additive      Additive           D         D²

    16                    19                3           9

    13                    16                3           9

    15                    14               -1          1

    17                    17                0          0

    20                    24                4         16

    26                    28                2          4

    25                    28                3          9

                                       ∑D=14   ∑D²= 48

For this study, the sample size n =  and the mean difference M_D = .

The SS_D =  , the variance s²
_D= , the standard error S_MD =  and your t value =  .

Please report values with no decimal place if it comes out a whole number, 1 decimal if it comes out that way, and round to two decimal places when it needs to be rounded.

Use the t- table to find the correct critical t-value for this hypothesis test (use .05)?    report 3 decimal places like the table

Is the difference found between groups in this study statistically significant?