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counting and probability junior
Problem
A or is placed in each of the nine squares in a -by- grid. Shown below is a sample configuration with three s in a line. How many configurations will have three s in a line and three s in a line?
(A)
(B)
(C)
(D)
Solution
We are given a 3x3 grid in the problem. Therefore, there are 9 possible spots for a triangle or circle to be placed, and we are then asked to choose any 3 possible positions in a row for either a triangle or circle. Thus we have which is equivalent to
Final answer
D