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Which of the following is correct:
- ... where c is a constant, f(.) is a monotonic function, x and y are random variable.
- ... where c is a constant, f(.) is a monotonic function and x and y are random variable.
This always gets me confused. Because x and y are of one kind (I don’t know if that is the proper word) and there should be an ‘and’ in between, but I’m not about whether not I should write an ‘and’ before the phrase too because it is the last item in a list (I mean it’s like saying: I bought apples, oranges, and bananas.).