What is the standard error of the difference between the mea

What is the standard error of the difference between the means?

Subject ID

% Correct Spaced Practice

% Correct for Concentrated Practice

Consider the table:

Getting the standard deviation of the differences (fourth column),

s = 22.0389266

Thus,

standard error of difference = s / sqrt(n) = 22.0389266/sqrt(15)

standard error of difference = 5.69042638 [ANSWER]

Subject ID	% Correct Spaced Practice	% Correct for Concentrated Practice	Difference (x1 - x2)
1	60	40	20
2	80	60	20
3	60	50	10
4	70	40	30
5	40	80	-40
6	50	70	-20
7	50	60	-10
8	70	50	20
9	70	40	30
10	60	50	10
11	80	60	20
12	70	50	20
13	60	30	30
14	50	70	-20
15	80	50	30