How many ways can you form a committee of 3 from a group of 10 people?

Practice Questions

Q1
How many ways can you form a committee of 3 from a group of 10 people?
  1. 120
  2. 90
  3. 80
  4. 100

Questions & Step-by-Step Solutions

How many ways can you form a committee of 3 from a group of 10 people?
  • Step 1: Understand that we want to choose 3 people from a group of 10.
  • Step 2: Recognize that the order in which we choose the people does not matter (i.e., choosing Alice, Bob, and Charlie is the same as choosing Charlie, Bob, and Alice).
  • Step 3: Use the combination formula, which is written as nCr, where n is the total number of people and r is the number of people to choose. The formula is nCr = n! / (r! * (n - r)!).
  • Step 4: In our case, n = 10 and r = 3. So we need to calculate 10C3.
  • Step 5: Plug the numbers into the formula: 10C3 = 10! / (3! * (10 - 3)!) = 10! / (3! * 7!).
  • Step 6: Calculate 10! = 10 × 9 × 8 × 7!, so we can cancel 7! in the numerator and denominator.
  • Step 7: Now we have 10C3 = (10 × 9 × 8) / (3 × 2 × 1).
  • Step 8: Calculate the numerator: 10 × 9 × 8 = 720.
  • Step 9: Calculate the denominator: 3 × 2 × 1 = 6.
  • Step 10: Divide the numerator by the denominator: 720 / 6 = 120.
  • Step 11: Therefore, there are 120 ways to form a committee of 3 from a group of 10 people.
  • Combinatorics – The study of counting, arrangements, and combinations of objects.
  • Binomial Coefficient – The formula used to determine the number of ways to choose a subset of items from a larger set, denoted as nCr.
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