Math Problem Statement
it is given that the permutation P(n, r) = 240 and combination C(n,r) = 120 find the value of r
Solution
We are given the following two equations:
We know the following formulas for permutations and combinations:
- Permutation:
- Combination:
To find the value of , let's divide the permutation formula by the combination formula, which eliminates and simplifies the equation:
Thus:
Simplifying:
Now, we solve for . The factorial of that equals 2 is:
Thus, the value of is 2.
Would you like further details or explanations? Here are 5 related questions for further understanding:
- How do you calculate for any given ?
- Can you explain why we divided by ?
- What is the difference between permutations and combinations?
- How does the factorial operation impact larger values of ?
- How would the equations change if and were larger numbers?
Tip: The division trick for simplifying and is useful when you need to eliminate complex factorials.
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Math Problem Analysis
Mathematical Concepts
Permutations
Combinations
Factorials
Formulas
Permutation: P(n, r) = n! / (n - r)!
Combination: C(n, r) = n! / (r!(n - r)!)
Theorems
Factorial Theorem
Suitable Grade Level
Grades 9-11
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