Aradio disc jockey has 7 songs on this upcoming hours playlist: 2 are rocks songs, 3 are reggae songs, and 2 are country songs . the disc jockey randomly chooses the first song to play , and then she randomly chooses the second song from the remaining ones. what is the probability that both songs are reggae songs ? write your answer as a fraction in simplest form?

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