A swimming coach needs to choose a team for a relay race. The coach must select 4 of 6 available swimmers and put them in a strategic sequence.How many unique ways are there to arrange 4 of the 6 swimmers?
Q. A swimming coach needs to choose a team for a relay race. The coach must select 4 of 6 available swimmers and put them in a strategic sequence.How many unique ways are there to arrange 4 of the 6 swimmers?
Select Swimmers: First, we need to select 4 swimmers out of the 6 available. This is a combination problem because the order in which we select the swimmers does not matter at this point.The number of ways to choose 4 swimmers from 6 is calculated using the combination formula:Number of combinations = 6C4=4!×(6−4)!6!
Calculate Combinations: Now we calculate the factorial values needed for the combination formula.6!=6×5×4×3×2×1=7204!=4×3×2×1=24(6−4)!=2!=2×1=2
Calculate Factorials: We substitute the factorial values into the combination formula to find the number of ways to choose 4 swimmers.6C4=(24×2)720
Substitute and Divide: Perform the division to find the number of combinations.6C4=487206C4=15This means there are 15 ways to choose 4 swimmers from 6.
Arrange Swimmers: Next, we need to arrange the 4 selected swimmers in a strategic sequence. This is a permutation problem because the order in which we arrange the swimmers matters.The number of ways to arrange 4 swimmers is calculated using the permutation formula for n objects taken r at a time:Number of permutations = P(n,r)=(n−r)!n!Since we have already chosen 4 swimmers, we need to arrange these 4, so n=r=4.
Calculate Permutations: We calculate the permutation for 4 swimmers.Number of permutations = P(4,4)=(4−4)!4!
Factorial Calculation: Now we calculate the factorial values needed for the permutation formula.4!=4×3×2×1=24(4−4)!=0!=1 (By definition, 0! is equal to 1)
Substitute and Find: We substitute the factorial values into the permutation formula to find the number of ways to arrange the swimmers.P(4,4)=124P(4,4)=24This means there are 24 ways to arrange 4 swimmers.
Multiply for Total: Finally, we multiply the number of combinations by the number of permutations to find the total number of unique ways to arrange 4 of the 6 swimmers.Total unique arrangements = Number of combinations × Number of permutationsTotal unique arrangements = 15×24
Perform Final Multiplication: Perform the multiplication to find the total number of unique arrangements.Total unique arrangements = 15×24Total unique arrangements = 360