A grab bag contains one chip with the number 1, two chips each with the number 2, three chips each with the number 3, ..., and n chips each with the number n, where n e Z+. All chips are of the same size, those numbered 1 to m are red, and those numbered m + 1 to n are blue, where m ∈ Z+ and m < n. If Casey draws one chip, what is the probability it is the chip with 1 on it, given that the chip is red?