(5.36) A study of class attendance and grades among first-year students at a state university showed that, in general, students who attended a higher percentage of their classes earned higher grades. Class attendance explained 36% of the variation in grade index among the students.
What is the numerical value of the correlation between the percentage of classes attended and the grade index?
a) 0.1296
b) 0.36
c) 0.6
d) -0.36
e) -0.6
f) -0.1296