Asked by Raj

How many different selections of four letters from the 12 letters of the word REFRIGERATOR contain no Rs and two Es?
Answered by Leo Galleguillos
I would start by breaking this down.

How many unique selections of four letters are there?
How many contain no R's?
How many contain exactly 2 E's?
Answered by Raj
Can I do it directly using 9/2! * 4!/4!
Answered by Raj
Let me know how you would do it?
Answered by bobpursley
https://math.stackexchange.com/questions/2872662/permutation-selection-of-4-letters-from-12
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