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How do you interpret permutations?
If the order doesn’t matter then we have a combination, if the order do matter then we have a permutation. One could say that a permutation is an ordered combination. The number of permutations of n objects taken r at a time is determined by the following formula: P(n,r)=n!
How do you tell the difference between a permutation and a combination problem?
| Difference between Permutation and Combination | |
|---|---|
| Multiple permutations can be derived from a single combination. | From a single permutation, only a single combination can be derived. |
| They can simply be defined as ordered elements. | They can simply be defined as unordered sets. |
What are the keywords to identify a combination or permutation situations?
The keywords like-selection, choose, pick, and combination-indicates that it is a combination question. Keywords like-arrangement, ordered, unique- indicates that it is a permutation question.
What’s the difference between a permutation and a combination?
Permutations are for lists (where order matters) and combinations are for groups (where order doesn’t matter). In other words: A permutation is an ordered combination. Note: A “combination” lock should really be called a “permutation” lock because the order that you put the numbers in matters.
How to count the number of permutations in a set?
For situations we encounter with larger sets it is too time-consuming to list out all of the possible permutations or combinations and count the end result. Fortunately, there are formulas that give us the number of permutations or combinations of n objects taken r at a time.
How to figure out how many combinations we have?
If we want to figure out how many combinations we have, we create all of the permutations and divide by all of the redundancies. In our case, we get 336 permutations (8 x 7 x 6), and we divide by the six redundancies for each permutation and get 336/6 = 56. Therefore, the general formula for a combination is: C (n,k) = P (n,k) / k!
What are the permutations of a blue ribbon?
Since the order in which ribbons are awarded is important, we need to use permutations. Blue ribbon: There are five choices: A B C D E. Let’s say A wins the blue ribbon. Red ribbon: There are four remaining choices: B C D E.