Mathematics 9709 · AS & A Level · Permutations and combinations

Permutations and combinations — practice question

Among a set of $25$ people, $6$ are swimmers, $8$ are cyclists and $11$ are runners. Every person takes part in just one of these sports. A team of $7$ people is chosen from these $25$ people to enter a competition.
(a)[4]

Determine the number of distinct ways to choose the team of $7$ if it contains exactly $1$ swimmer, at least $4$ cyclists and at most $2$ runners.

(b)[2]

In a different competition, a team of $9$ people includes $2$ swimmers, $3$ cyclists and $4$ runners. The team members line up for a photograph. How many distinct line-ups are possible for the $9$ people if the swimmers stay together, the cyclists stay together and the runners stay together?

(c)[4]

How many distinct line-ups are there of the $9$ people if no two cyclists are adjacent?

Worked solution & mark scheme

This 10-mark question has a full step-by-step worked solution and mark scheme. One marking point: Valid use of combinations across the different cases.

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