Ms. Roth has to arrange her High School choir into rows. The first row has spots for 4 sopranos, and there are a total of 5 sopranos in the choir. How many ways can Ms. Roth arrange the sopranos in the first row?
Question
Ms. Roth has to arrange her High School choir into rows. The first row has spots for 4 sopranos, and there are a total of 5 sopranos in the choir. How many ways can Ms. Roth arrange the sopranos in the first row?
Solution
This is a permutation problem. Permutations are used when the order of items matters. In this case, the order in which the sopranos are arranged in the first row matters.
The formula for permutations is:
P(n, r) = n! / (n-r)!
where:
- n is the total number of items,
- r is the number of items to choose,
- "!" denotes factorial, which means multiplying all positive integers up to that number.
In this case, n = 5 (the total number of sopranos) and r = 4 (the number of sopranos to be arranged in the first row).
So, the number of ways Ms. Roth can arrange the sopranos in the first row is:
P(5, 4) = 5! / (5-4)!
= 120 / 1
= 120 ways.
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