In the same way, to have a particular pair (ai,aj) fixed, we can choose any permutation of the remaining n−2 elements; there are (n−2)! such choices and thus \[P(A_i \cap A_j) = \fra...In the same way, to have a particular pair (ai,aj) fixed, we can choose any permutation of the remaining n−2 elements; there are (n−2)! such choices and thus P(Ai∩Aj)=(n−2)!n!=1n(n−1). The number of terms of this form in the right side of Equation [eq 3.5] is (n2)=n(n−1)2!. Hence, the second term of Equation [eq 3.5] is −n(n−1)2!⋅1n(n−1)=−12!. Similarly, for any specifi…
