Explanation
This answer states that number of passed test cases divided by total number of test cases is how the success rate is calculated after completing user acceptance testing (UAT) for a Commerce Cloud implementation at CK. Test cases are scenarios or steps that verify or validate if a feature or a functionality meets the acceptance criteria or requirements. Passed test cases are test cases that meet or pass the acceptance criteria or requirements. Total number of test cases are all test cases that are executed or performed for UAT. Number of passed test cases divided by total number of test cases is how the success rate is calculated because it measures how many test cases meet or pass the acceptance criteria or requirements out of all test cases executed or performed for UAT.
References:https://trailhead.salesforce.com/en/content/learn/modules/salesforce-business-analyst-quick-look/use

A gap analysis is a document that compares the current state with the desired future state of a process or system, identifies what needs to change or improve, and recommends actions or solutions to bridge the gap. A gap analysis can help CK understand how to enhance its user experience for customer service agents on Service Cloud so they can effectively meet their service-level agreements. A change management document is a document that outlines how changes will be planned, implemented, communicated, monitored, controlled, etc., during a project lifecycle