We need to choose a team of 11 from a pool of 15 players and also select a captain. Find the number of different ways this can be done.
We need to choose a team of 11 from a pool of 15 players and also select a captain. Find the number of different ways this can be done.
(A) $\binom{15}{11}$,
(B) $11 \times \binom{15}{11}$,
(C) $15 \times 14 \times \cdots \times 5$,
(D) $(15 \times 14 \times \cdots \times 5) \times 11$.
Answer: (B) $11 \times \binom{15}{11}$
Explanation:
Number of ways of selecting a captain from 15 players = $\binom{15}{1}$.
Remaining players in the pool $= 15 - 1 = 14$, and the remaining number of players to be chosen $= 11 - 1 = 10$.
Number of ways of selecting 10 players from a pool of 14 players = $\binom{14}{10}$.
Therefore, the total number of different ways of selecting 11 players from a pool of 15 players and also select a captain is
$= \binom{15}{1} \times \binom{14}{10}$
$= 15 \times \frac{14 \times 13 \times 12 \times 11 \times 10!}{4! \times 10!}$
$= \frac{15 \times 14 \times 13 \times 12 \times 11!}{4! \times 11!} \times 11$
$= \binom{15}{11} \times 11$.
Comments
Post a Comment