A student is to answer 5 out of 10 questions on an examination. In how many ways can he make the selection if (a) there are no restrictions? (b) he must answer the first three questions? (c) he must answer at least three of the first six questions?
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This is a combination problem, because the order in which the questions are chosen does not matter. The number of ways to choose 5 questions out of 10 is given by the combination formula C(n, r) = n! / [r!(n-r)!], where n is the total number of items, r is the Show more…
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