Question

List all the ways to select two members from S with repetition. The order in which the members are selected is not important. For example, DD is allowed and BA is the same selection as AB.

S = (K,L,M,N,P)
Identify the list of all the ways to select two members from S, allowing for repetition.

Answer 1

9514 1404 393

Answer:

KK KL KM KN KP LL LM LN LP MM MN MP NN NP PP

Explanation:

Instead of starting with adjacent letters in the list, we start with the same letter. There are 15 possible pairs.

KK KL KM KN KP LL LM LN LP MM MN MP NN NP PP

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Additional comment

We leave out pairs with letters previous, because you've said KL is the same as LK, and KL has already been listed. The problem with this list is that it misstates the probabilities of randomly obtaining a given pair. It is not 1/15, but is 2/25 for all but letter duplicates. For duplicates (KK), the probability is 1/25, not 1/15.