hi i need help calculating the standard error using the central limit theorem.

Question

*a population of scores contains exactly 5 scores : 2, 3, 6, 8, 11, there are 5x5=25 samples of the two scores (n=2)*

i already calculated the standard deviation and mean. for the question my standard deviation was 3.6742 and my mean was 6.

i also need to calculate the standard deviation of the following sampling distribution of means. apparently this is the longhanded way of calculating standard error.

(2, 2) ... 2
(2, 3) ... 2.5
(2, 6) ... 4
(2, 8) ... 5
(2, 11) ... 6.5
(3, 2) ... 2.5
(3, 3) ... 3
(3, 6) ... 4.5
(3, 8) ... 5.5
(3, 11) ... 7
(6, 2) ... 4
(6, 3) ... 4,5
(6, 6) ... 6
(6, 8) ... 7
(6, 11) ... 8.5
(8, 2) ... 5
(8, 3) ... 5,5
(8, 6) ... 7
(8, 8) ... 8
(8, 11) ... 9.5
(11, 2) ... 6,5
(11, 3) ... 7
(11, 6) ... 8,5
(11, 8) ... 9,5
(11, 11) ... 11

thank you :)