OpenStudy (lifeisadangerousgame):

You are creating your highschool schedule and you get to pick what times you take each class. You have Geometry, Earth Science, English Literature, Ancient History and Music Appreciation. You have 7 class periods to choose from. How many different ways can you arrange your schedule? Help with this please?

4 years ago
OpenStudy (phi):

Each subject can be assigned to a "class period" For Geometry, we pick any of the 7 available. that leaves 6 for the next subject, then 5, and so on. we have 7*6*5*4*3 ways to make the assignments.

4 years ago
OpenStudy (phi):

order matters so this is a permutation. repetition is not allowed (once we assign a class period, we can't re-use it) see http://www.mathsisfun.com/combinatorics/combinations-permutations.html for a short explanation... under permutations without repetition

4 years ago
OpenStudy (lifeisadangerousgame):

So I multiply 7*6*5*4*3, do I not include 2? Thank you for your help!

4 years ago
OpenStudy (phi):

we use 5 numbers because we have 5 subjects.

4 years ago
OpenStudy (phi):

if we had just 1 subject, and 7 class periods we have 7 choices for what period we assign if we had 2 subjects, we could assign 1 of the 7 periods to the first subject, and 6 to the 2nd subject. We would have 7*6 = 35 ways to make those assignments. (If you get bored, and want to fill your time, try finding all 35 ways)

4 years ago