What correlation would you expect between students’ grades and class attendance?

A study of class attendance and grades among first-year students at a state university show that in general students who attended a higher percent of their classes earned higher grades. Class attendance explained 16% of the variation in grade index among the students. What is the numerical value of the correlation between percent of classes attended and grade index?

State the null and alternative hypotheses for each of the following potential research questions. In each situation, also indicate whether the hypothesis test will be one-sided or two-sided. Do female college students study more, on average, than male college students do? Compared to men who are not bald, are bald men more likely to have heart disease? Is there a correlation between height and head circumference?