Probability Distribution from a Graph

In a class of 30 students, the results of a math test are displayed in the graph below. The graph shows the number of students who scored within the following ranges:

Score Range:

0-20: 5 students

21-40: 10 students

41-60: 8 students

61-80: 4 students

81-100: 3 students

If a student is chosen at random, what is the probability that the student scored more than 40 on the test?