9. Evaluate: C (7,4) A. 5 B. 15 C. 25 D. 35 10. The first ten letters of the English alphabet are to be used by a certain company as employee codes in sets of five. Find the number of combinations. A. 25 B. 225 C. 252 D. 552
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The formula for combinations is C(n, r) = n! / (r!(n-r)!), where n is the total number of items and r is the number of items taken at a time. Plugging in the values, we have C(7,4) = 7! / (4!(7-4)!) = 7! / (4!3!) = (7 * 6 * 5 * 4!) / (4! * 3 * 2 * 1) = (7 * 6 Show more…
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