Analysis of moodle quizzes compared to grades

In Mathematics class in first year of study here in Faculty of Civil and Geodetic Engineering we use moodle quizzes as a tool to limit the number of students allowed to take (optional) tests. Each week the student has to solve a quiz with five questions, each question can be repeated as many times as they want until they answers it correctly. We will look at the correlation between the number of these repetitions and the score achieved on the test.