I have an exam that users on the site will take. The questions have been divided into four categories:
- Algebra
- Fractions
- Logic
- Probability.
As of now questions for probability are very few in number. I am trying to decide what are strengths and weaknesses of a user who takes the exam. I know that: $\frac{\text{specific category answered correctly}}{\text{number of category questions answered}}$ would be a possible solution. But I feel that this would be skewed in terms of categories like probability where the question numbers are few so getting one right would marginally increase the ratio. My question is there a better way to calculate this rather than just simple ratios.