Question
Decide whether you would use a permutation, a combination, or neither. Next, write the solution using permutation notation or combination notation, if possible, and, finally, answer the question.
A club with 31 members is to select five officers (president, vice president, secretary, treasurer, and historian). In how many ways can this be done?
I came up with 155 ways,
Thank you and Good afternoon
A club with 31 members is to select five officers (president, vice president, secretary, treasurer, and historian). In how many ways can this be done?
I came up with 155 ways,
Thank you and Good afternoon
Answers
It is not combinations because the order matters, it is permutations. (Joe could be either president or vice president for example and those are not the same)
31!/(31-5)!
= 31!/26!
= 31*30*29*28*27
= 20,389,320
31!/(31-5)!
= 31!/26!
= 31*30*29*28*27
= 20,389,320
thank you Damon I took notes to see how if falls into place.
You are welcome.
This is a good example to diiferentiate between combinations and permutations
Combinations of 31 taken 5 at a time would be
31! /[ 5! (31-5)! ]
That takes into account all the different groups of five you can make, but does not order the five for specific office.
If you now require a different choice for every office within the group of 5, you will get 5! or 120 times as many arrangements
20,389,320 / 120 = 169,911
so I do not know where you got 155
This is a good example to diiferentiate between combinations and permutations
Combinations of 31 taken 5 at a time would be
31! /[ 5! (31-5)! ]
That takes into account all the different groups of five you can make, but does not order the five for specific office.
If you now require a different choice for every office within the group of 5, you will get 5! or 120 times as many arrangements
20,389,320 / 120 = 169,911
so I do not know where you got 155
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