## Thursday, May 14, 2009

### BOB on Permutations and Combinations

Sup y'all~ Here I am BOB-ing the night before our scheduled unit test, however I'm not quite sure if I am writing the test tomorrow, so I shall BOB anyway!

Well, it's certain that I found it a lot easier than Logarithms! I actually got the hang of it at first, I even predicted (n-1)! However, things got trickier and trickier~

The concepts I had a hard time grasping were the table problems and the poker hands (mainly because I'm terrible at card games and am extremely unfamiliar with these "hands!")! So I definitely need to practice those...

What I learned from this unit is to create and utilize even more clever ideas! Without them, this unit would be a big toughie! So remember, read the question carefully, know what it's asking for, and think of a clever way to find a solution!

Also, those necklaces and bracelets! Keep in mind that those things can be turned over and result in a permutation that you've already come up with before. So, you must divide your answer by two! OH! This does not apply to tables lol. Because you can't turn a table over when there are people sitting there, that's just rude.

Hmm.. what else?
Well, with permutations, order matters...
However, with combinations, order does not matter!

Don't forget about the "Pick" (nPr) and "Choose" (nCr) formulas and when they are appropriate to use!

Well, isn't this BOB post all over the place :/
Oh well!

Oooh, don't forget about using them bags, they're quite helpful, but also - don't forget that the objects within each bag still have a number of ways to be rearranged!

Speaking of objects, don't forget about distinguishible and non-distingquishable objects!
That is... (n!)/(k1!)(k2!)(k3!)
Where n = number of objects and k1, k2, k3 are the numbers of each non-distinguishable object!

Aw man, I'm BOB'd out. Sorry if I missed anything, every else had already made such awesome posts anyway!

Good luck everyone! Do your best!