Forming a Team of Professionals

From ten people, how many ways can you form a team of eight people consisting of a project manager, two (equivalent) deputy project managers, and five (equivalent) engineers?


The answer is 7560.

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3 solutions

Toby M
Feb 17, 2021

The project manager can be picked in 10 10 ways. The deputy project managers (indistinguishable) can be picked in 9 × 8 2 ! \frac{9 \times 8}{2!} ways, and by the same reasoning, the engineers can be chosen in 7 × 6 × 5 × 4 × 3 5 ! \frac{7 \times 6 \times 5 \times 4 \times 3}{5!} ways.

In total, there are 10 × 9 × 8 2 ! × 7 × 6 × 5 × 4 × 3 5 ! = 7560 10 \times \frac{9 \times 8}{2!} \times \frac{7 \times 6 \times 5 \times 4 \times 3}{5!} = 7560 ways to form the team.

Sathvik Acharya
Feb 17, 2021

Number of ways of picking 8 8 people from a group of 10 10 is, ( 10 8 ) = 45 {10 \choose 8 }=45 Number of ways of picking 5 5 engineers from the above 8 8 people is, ( 8 5 ) = 56 {8 \choose {5}}=56 Number of ways of picking 2 2 deputy project managers from the 3 3 people left is, ( 3 2 ) = 3 {3\choose 2}=3 Number of ways of picking 1 1 project manager from the 1 1 person left is, ( 1 1 ) = 1 {1\choose 1}=1 Therefore, the total ways of to form a team meeting the required conditions is, ( 10 8 ) ( 8 5 ) ( 3 2 ) ( 1 1 ) = 45 56 3 1 = 7560 {10 \choose 8}\cdot {8 \choose 5}\cdot {3\choose 2}\cdot {1\choose 1}=45\cdot 56\cdot 3\cdot 1=\boxed{7560}

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Sathvik Acharya - 3 months, 3 weeks ago

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