Many people wants to know how they can pass PSM I exam. Here is my experience:
1- I read Scrum Guide carefully many times.
2- I tried Scrum Open Assessment a lot of time until get 100% score during 10 minutes.
3- I read carefully following book: "Scrum Narrative & PSM exam guide by Muhammed Musthafa Soukath Ali." This book contains a complete test. Also, Muhammed has another good book for PSPO I exam which its name is : "The Professional Scrum Product Owner."