Item 1 Dr. Larson was interested in whether classical music helps students perform better on a test. Dr. Larson randomly assigned half of the study's participants to a group that listened to classical music while taking a test. The other half of the participants did not listen to music while taking a test. The research design Dr. Larson used is

Set $r$ is a set of rectangles such that (1) only the grid points shown here are used as vertices, (2) all sides are vertical or horizontal and (3) no two rectangles in the set are congruent. if $r$ contains the maximum possible number of rectangles given these conditions, what fraction of the rectangles in set $r$ are squares? express your answer as a common fraction.

"which statement is necessarily true if bd is an altitude to the hypotenuse of right ? abc? a.) ? adb? ? bdc b.) ? adb~? bdc c.) abbc=acbd d.) ? bac? ? bdc"

Suppose the equation ||x-a|-b|=2008 has 3 distinct real roots and a not =0. find the value of b.