Math Problem Statement
A group of 2 students is to be chosen from a 30-member class to represent the class on the student council. How many ways can this be done? (NOTE: Order of the selection is not important.)
Answer: ways
Solution
Since the order of selection is not important, we are dealing with a combination problem. The formula for combinations is:
In this case:
- (the total number of students),
- (the number of students to be chosen).
Substitute these values into the formula:
Simplify this expression by canceling from the numerator and denominator:
So, there are 435 ways to choose 2 students from a class of 30.
Answer: 435 ways
Would you like a further breakdown or explanation?
- How would the calculation change if we had to select 3 students instead of 2?
- How many ways can we select a group of 5 students from the same class?
- What if the order of selection mattered? How many ways could 2 students be chosen then?
- Can you calculate the number of ways to choose 2 students from a class of 50?
- How would the approach differ if we had 10 students and needed to form a team of 4?
Tip: When the order of selection doesn't matter, always use combinations, not permutations.
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Math Problem Analysis
Mathematical Concepts
Combinations
Counting Principles
Formulas
Combination formula C(n, r) = n! / (r!(n - r)!)
Theorems
Combination theorem for selection without regard to order
Suitable Grade Level
Grades 10-12
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