While I was studying metric spaces, I saw this question on the book:
Let $Q$ be the set of all rational numbers. What are $intQ$ and $∂Q$?
I think the answer should be: $intQ$ is all the rational numbers, and the $∂Q$ is all the real numbers. But I do not have the answer and do not feel confident with my answer. Is my answer true?
edit: To make it clear why I though $intQ$ is all the rational numbers: if I take $X_0$ = 3/2 and r=1, $(X_0-r,X_0+r)$ is a subset of $Q$ and as long as I choose $X_0$ a rational number, for all values of r, I can get a rational number.