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counting and probability senior

Problem

The numbers are randomly placed into the squares of a grid. Each square gets one number, and each of the numbers is used once. What is the probability that the sum of the numbers in each row and each column is odd?
(A)
(B)
(C)
(D)
Solution
Note that odd sums can only be formed by or so we focus on placing the evens: we need to have each even be with another even in each row/column. Because there are only 5 odd numbers overall, we can only have 1 row and 1 column. It can be seen that there are ways to do this. There are then ways to permute the odd numbers, and ways to permute the even numbers, thus giving the answer as .
Final answer
B