11. In math class, the teacher gave the students in a certain class 2 questions, stipulating that getting one question right earns 10 points, half right and half wrong earns 5 points, and completely wrong or not doing it earns 0 points. After grading, the teacher found that all scoring situations were present in the class, and students with the same score and the same scoring situation for each question were all 5 people. So, this class has $\qquad$ students.
【Analysis】 $5 \times 9=45$ students.
【Firstly, analyze the score situation, the tree diagram shows there are 9 possible outcomes, since the number of people in each case is the same and all are 5 people, so it is 45 people】