Amath class had 5 girls and 5 boys in the seventh grade and 1 girl and 7 boys in the eight grade. the teacher randomly selects a seventh grader and an eight grader from the class for a competition. what is the probability that the students she select are both boys?

Apinhole camera is made out of a light-tight box with a piece of film attached to one side and pinhole on the opposite side. the optimum diameter d(in millimeters) of the pinhole can be modeled by d=1.9[ (5.5 x 10^-4) l) ] ^1/2, where l is the length of the camera box (in millimeters). what is the optimum diameter for a pinhole camera if the camera box has a length of 10 centimeters