Using Quizzes for practice and assessment
6. Viewing quiz results
To see the grades once students have done your quiz, you can either: 
— click the quiz itself and then the link 'Attempts =' (where the number is the number of attempts)  - or - 
— click the quiz and then from the block Administration > Quiz administration, expand 'Results' and select the analysis you need.
You may want to have more details on quiz reports by reading the MoodleDocs page on this topic.