SSwithin = SX2 -
(Sxboys)2 (Sxgirls)2
nboys
ngirls
= 585-
(5+7+6+8+9)2 (6+9+7+8+10)2
5
= 585 -
352
402
= 585- (245 + 320)
= 585 - 565 = 20
Variancewithin = 20/8 = 2.5