An 85% pass mark sounds brutal, and the Scrum Guide is short enough to read in an evening, so candidates tend to assume PSM I is either impossible or trivial. Both beliefs cost attempts. The exam has 80 questions in 60 minutes and costs USD 200, and if every question counts equally you can miss about 12. What decides the result is how closely you have read a very short document, not how much Scrum experience you bring.

This guide is about passing PSM I itself: how deep to take the Scrum Guide, how the questions are phrased, how to use Scrum.org's open assessments, and how to run the hour on exam day. It is written for first-time candidates, for practising Scrum Masters who assume experience is enough, and for people retaking after a near miss.
Is the short Scrum Guide really all you need to pass PSM I?
Almost, but only if you read it the way a lawyer reads a contract. The current Guide, the 2020 edition that Scrum.org explains on its Scrum Guide 2020 update page, runs to only a few pages. Every word in it was chosen on purpose, which is why the exam can ask about a single verb. A sentence such as "the Product Owner is one person, not a committee" is a complete exam question waiting to be asked.