Expression 9: Start sum from "h" equals "A" to "N" minus "B" , end sum, left parenthesis, Start sum from "k" equals "B" to "N" minus "h" , end sum, left parenthesis, nCr left parenthesis, "N" , "h" , right parenthesis times nCr left parenthesis, "N" minus "h" , "k" , right parenthesis times "p" Superscript, "h" , Baseline times "q" Superscript, "k" , Baseline times left parenthesis, 1 minus "p" minus "q" , right parenthesis Superscript, "N" minus "h" minus "k" , Baseline , right parenthesis , right parenthesisN−B∑h=AN−h∑k=BnCrN,h·nCrN−h,k·ph·qk·1−p−qN−h−k