Hi,
Based on what you are saying, looks like it's the very beginning of a journey for you.
The case is not about 100% correct answer. It's about the process, communication, etc. Thus. it's really hard to assess your performance based on what you are saying. But 20 cases is usually not enough. Try to do at least 20 more, with great partners who can give you qualified feedback.
Here is what's being assessed:
Cases:
1. Structuring
-Initial structure
-Structuring through the case
-Business judgment
2. Math
-Calculations – a) correct b) efficient c) fast
-Analyzing charts and tables
3. Creativity
-Structuring creativity questions
-Business judgment
4. Conclusions / communication
-Synthesis through the case
-Final recommendation
Fit:
1. Your background and Motivation
-Tell me about yourself / walk me through your resume
-Why Consulting?
-Why Company
2. Key competencies (stories)
-Leadership
-Conflict / Persuasion / Personal impact
-Achievement / Entrepreneurial drive
3. Other questions (Interviewers favorite questions)
-Strengths / weaknesses
-Biggest failure, etc
4. Your questions to the interviewer
Best