Probability- precalc permutation and combination

In summary, permutations and combinations are both methods used to arrange or select objects from a larger set. Permutations involve arranging objects in a specific order, while combinations involve selecting objects without regard to order. The formulas for calculating permutations and combinations are nPr = n!/(n-r)! and nCr = n!/(r!(n-r)!), respectively. Both can be used to solve real-world problems, such as calculating possible outcomes or arrangements. The main difference between with and without replacement in permutations and combinations is whether an object can be chosen more than once. Finally, the choice between permutations and combinations depends on whether the order of objects matters in the problem at hand.
  • #1
Roni1985
201
0

Homework Statement


P(4,2)+C(5,3)


Homework Equations




The Attempt at a Solution



I think I'm missing something, P(4,2)= 4P2 and C(5,3)=5C3 ?
 
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  • #2
Hi Roni1985! :wink:
Roni1985 said:
P(4,2)= 4P2 and C(5,3)=5C3 ?

I assume so. :smile:
 
  • #3
tiny-tim said:
Hi Roni1985! :wink:


I assume so. :smile:

I see.. thanks :)
 

What is the difference between permutations and combinations?

Permutations refer to the arrangement of a set of objects in a specific order, while combinations refer to the selection of a subset of objects from a larger set without regard to order.

How do I calculate the number of permutations or combinations?

The formula for permutations is nPr = n!/(n-r)!, where n is the total number of objects and r is the number of objects in each arrangement. The formula for combinations is nCr = n!/(r!(n-r)!), where n is the total number of objects and r is the number of objects in each combination.

Can permutations or combinations be used to solve real-world problems?

Yes, both permutations and combinations can be used to solve real-world problems such as calculating the number of possible outcomes in a game or determining the number of different ways to arrange a group of people in a line.

What is the difference between with and without replacement in permutations and combinations?

In permutations and combinations, with replacement means that an object can be chosen more than once, while without replacement means that an object can only be chosen once.

How do I know when to use permutations or combinations in a problem?

Permutations should be used when the order of objects matters, such as arranging letters in a word. Combinations should be used when the order of objects does not matter, such as choosing a group of people for a committee.

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