What is the probability of rolling a sum of 8 on two fair six-sided dice?
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What is the average weight of 20 students in a class if their weights are 120, 130, 135, 140, 125, 130, 135, 150, 155, 125, 130, 140, 135, 130, 145, 160, 155, 150, 135, and 140 pounds?
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What are the necessary and sufficient conditions for triangles ABC and DEF to be congruent?