Explanation:
To read these kinds of graphs, each dot represents an instance of each event on the x-axis
meaning if there are 2 dots over 80, kim made 2 80s on two different quizzes
so you could do something like this to find the mean of kim's
((2 x 80) + 85 + 95 + (2 x 100)) / 6 quizzes
and do the same for the other and compare means