Questions: The professor in this class would like to organize a committee to help critique a new textbook. i. How many different five-person committees can be formed? ii. How many different all male five-person committees can be formed? iii. How many different all female five-person committees can be formed? iv. Use your responses to parts (ii) and (iii) above to find how many five-person committees with mixed gender representation can be formed.

The professor in this class would like to organize a committee to help critique a new textbook.
i. How many different five-person committees can be formed?
ii. How many different all male five-person committees can be formed?
iii. How many different all female five-person committees can be formed?
iv. Use your responses to parts (ii) and (iii) above to find how many five-person committees with mixed gender representation can be formed.
Transcript text: The professor in this class would like to organize a committee to help critique a new textbook. i. How many different five-person committees can be formed? ii. How many different all male five-person committees can be formed? iii. How many different all female five-person committees can be formed? iv. Use your responses to parts (ii) and (iii) above to find how many five-person committees with mixed gender representation can be formed.
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Solution

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Solution Steps

To solve these questions, we need to use combinations, as the order of selection does not matter. We will calculate the total number of five-person committees, then calculate the number of all-male and all-female committees separately. Finally, we will use these results to find the number of mixed-gender committees by subtracting the all-male and all-female committees from the total.

Step 1: Calculate Total Number of Five-Person Committees

To find the total number of five-person committees that can be formed from 20 people, we use the combination formula:

\[ \binom{n}{r} = \frac{n!}{r!(n-r)!} \]

where \( n = 20 \) and \( r = 5 \). Thus, the total number of committees is:

\[ \binom{20}{5} = \frac{20!}{5!(20-5)!} = 15504 \]

Step 2: Calculate All-Male Five-Person Committees

To find the number of all-male five-person committees, we use the same combination formula with \( n = 12 \) (the number of males) and \( r = 5 \):

\[ \binom{12}{5} = \frac{12!}{5!(12-5)!} = 792 \]

Step 3: Calculate All-Female Five-Person Committees

Similarly, to find the number of all-female five-person committees, we use the combination formula with \( n = 8 \) (the number of females) and \( r = 5 \):

\[ \binom{8}{5} = \frac{8!}{5!(8-5)!} = 56 \]

Step 4: Calculate Mixed-Gender Five-Person Committees

To find the number of mixed-gender five-person committees, we subtract the number of all-male and all-female committees from the total number of committees:

\[ \text{Mixed-gender committees} = 15504 - 792 - 56 = 14656 \]

Final Answer

  • Total number of five-person committees: \(\boxed{15504}\)
  • All-male five-person committees: \(\boxed{792}\)
  • All-female five-person committees: \(\boxed{56}\)
  • Mixed-gender five-person committees: \(\boxed{14656}\)
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