Would Duaa be accepted even with limited ability

السلام عليكم ورحمة الله وبركاته I am a student preparing for an upcoming medical exam. I have been making duaa since Ramadan that I get a certain score in my medical exam that I knew it is extremely hard for me to get despite my efforts. I have recently changed my duaa to get a perfect score in the exam. This score I knew is IMPOSSIBLE for me to get regardless of my work. So, is it permissible to ask Allah of such duaa or not? I also alhamdulillah, all thanks to Allah I pray at masjid and I do my best in my worship and in my studying but the stimulation exams show results very far from the perfect score I am dreaming of