Answer
We can say with 95% confidence that the mean difference is between -3.39 and 0.16.
Work Step by Step
Here we have α = 0.05 and n = 7. df = 7 - 1 = 6
α/2 = 0.025
Using Student's t distribution table, we have:
$t^{*} = 2.447$
$E = t^{*} . s_{d}/\sqrt n$
$ = 2.447. 1.915/\sqrt 7 = 2.447 \times 0.724 = 1.771$
$\bar d - E = -1.614 - 1.771 = -3.39$
$\bar d + E = -1.614 + 1.771 = 0.16$
