Mine was 7 pages.
I also included a cover letter stating that my sample was an excerpt from a memo I submitted for my first year legal writing course. I went on to explain that I had worked with a partner on the assignment, and excluded portions of the discussion section that were my partner's work. I noted that it was originally a 15 page memo, and had been reduced to 7 pages. I also noted that I had incorporated minor editing suggestions into the memo.
It is probably obvious that if you use a class memo, you will have incorporated editing suggestions. Regardless, I wanted to go the "full disclosure" route so that I wouldnt be accused of submitting something that was not wholly my work.