The number of arrangements of the letters of the word BANANA in which ...
In BANANA. Letter A reapets 3 times and N reapets 2 times.
Total number of arrangements of word BANANA is

Let both N s are appear together, then they are considered is single letter.
In this way total number of arrangements are

Hence total number of arrangements where N do not appear adjacently is = 60 - 20 = 40
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The number of arrangements of the letters of the word BANANA in which ...
We can start by considering the total number of arrangements of the letters in BANANA, which is 6! (since there are 6 letters in total). However, this counts all arrangements, including those where the two N's are not together.
To eliminate these arrangements, we can treat the two N's as a single "letter" and consider the number of arrangements of the resulting 5 "letters" (B, A, N, A, A). This gives us 5! arrangements.
However, we have overcounted the arrangements where the two A's are indistinguishable. Specifically, for each arrangement where the two A's are swapped, we have counted it twice. There are 2! = 2 ways to swap the A's, so we need to divide our count by 2 to correct for this.
Therefore, the final answer is:
5!/2 = 60/2 = 30 arrangements.