How to address this question?
First, we need to see that we are asked: “in how many ways a set can be selected”.
As per the definition of a set, we should know that the elements in a set don’t have an order. In other words, a set is an unordered collection of elements.
So, the set {a,b} is the same as the set {b,a}.
With this information, you should realize that we need to use combinations (and not permutations).
So, the English alphabet has 26 letters, and we should answer how many 5-combinations can be selected from a set of 26 elements.
C(26,5) =
= 26!/5!(26-5)!
=26*25*24*23*22*21!/5!21!
=7893600/120
=65780
Answer:
We can select a set of five letters from the English alphabet in 65780 ways.
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