Exercises: Use Permutations and Combinations to Compute Probabilities

Work through each section in order. Before computing a count, ask the deciding question: "If I swap two of my chosen items, is it a DIFFERENT outcome?" If yes, order matters — use a permutation, nPr = n!/(n - r)!. If no, order does not matter — use a combination, nCr = nPr / r! = n!/(r!(n - r)!). For probabilities, count the favorable and the total the SAME way (both ordered or both unordered).