deletions | additions       diff --git a/We_can_define_the_within__.tex b/We_can_define_the_within__.tex  index 25b5564..268801a 100644  --- a/We_can_define_the_within__.tex  +++ b/We_can_define_the_within__.tex 
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We can define the within-class variance as the weighted sum of the variances of each cluster:  $$\sigma^2_{\text{Within}}(2) $$\sigma^2_{\text{Within}}(T)  = n_B(T)\sigma^2_B(T)+n_O(T)\sigma^2_O(T)$$ where