Right and Wrong Permutations and Combinations Methods And Pointers That Will Make You Ace These On Your CSET Exam

Notice that in this problem, the order in which you select the shirts does not matter, therefore we will use the combination formula.

The number we plug in for n is 7 because we have a total of 7 shirts to choose from. The number we plug in for k is 4 because we will only select 4 shirts.

Notice that when the same name appears in both the numerator and the denominator, we can cancel those numbers out.

Probability and Permutations

Most probability problems can be solved using the easier counting principle. Nevertheless, I’m going to show you that permutations can be used to solve probability problems.

Example: Two cards are drawn at random from a standard deck of 52 cards, without replacement. What is the probability that both cards drawn are kings?

We know that the 52 card deck has 4 kings and that we need the odds for drawing 2.

We know that overall, we are drawing 2 cards from a deck of 52 cards.

Therefore, plugging this information into the formula above gives us:

Permutations and Combinations Calculator

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