Question 1083881
sd for Brown is 4.06
sd for black is 3.38
+/- 1 sd for brown is 12.4+/- 4.06=(7.94, 16.46)
+/- 1 sd for black is 13.5 +/- 3.38 =(10.12, 16.88)
Note, the sd was a lot smaller than given.
Roughly 2/3 of the data should fit between +/- 1 sd, and if it doesn't, re-calculate it.