I am writing a statement of purpose right now for US graduate schools in mathematics, and am I bit bogged down on figuring out the approximate ratio of my background versus my actual research goals. I currently have three paragrahs of background, mainly involving seminars and projects, and a discussion of the non-traditionality of my situation, and one of my actual research goals, and I am trying to determine if this is what is desired? The only source of examples I could find are here, and I am not sure if these are actually good examples of what is desired.
Edit: I keep using the wrong word since statement of purpose and Personal statement means different things to different departments (for example, Northwestern seems to want only one essay, which they call a personal statement)