Explain two different methods for using combinations

Both methods produce the same answer: 50 C 45 = 2118760. In summary, there are two methods for using combinations to determine which students go on the bus and they both result in the same answer.
  • #1
kerrwilk
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Homework Statement



A soccer coach organizing a field trip finds that 50 students have signed up. However, the bus has only 47 seats, so a few students will have to travel by car. The coach and one other coach must go on the bus. Explain two different methods for using combinations to find how each coach can choose which students go on the bus. Show that both methods produce the same answer.

Homework Equations





The Attempt at a Solution



I determined that the number of combinations of students on the bus is 50 C 45 = 2118760. However, I do not know how this can be done with two different methods. Could someone please help me? Thanks.
 
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  • #2


I am not certain to what the question is referring, but it could be the following: for every 45 students that travel by bus there are 5 students that travel by car. We can either choose the 45 bus students (method 1) or we can choose the 5 car students (method 2).
 

1. What is the definition of combinations?

Combinations refer to the selection of unordered elements from a given set, without repetition. It is a mathematical concept used to determine the number of ways to select a subset of items from a larger set.

2. What is the difference between combinations and permutations?

The main difference between combinations and permutations is that permutations take into account the order of the elements, while combinations do not. In other words, combinations are concerned with the selection of elements, while permutations are concerned with the arrangement of elements.

3. What is the formula for calculating combinations?

The formula for calculating combinations is nCr = n! / (r! * (n-r)!), where n represents the total number of items in the set and r represents the number of items to be selected.

4. What are the two methods for using combinations?

The two methods for using combinations are the "n choose r" method and the Pascal's triangle method. The "n choose r" method involves using the formula nCr = n! / (r! * (n-r)!) to calculate the number of combinations. The Pascal's triangle method involves constructing a triangular pattern of numbers, where each number is the sum of the two numbers above it, and the number of combinations is represented by the numbers in the diagonal rows.

5. How are combinations used in real life?

Combinations are used in various fields, such as mathematics, statistics, and computer science, to solve problems involving selection and grouping. They are also used in everyday situations, such as when choosing a lottery ticket or creating a password for a computer system.

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