Name the values of the given digits in 5s in 6,755?

Can someone me with my hwplz(only the circled ones)

Suppose i flip two identical coins. what is the probability that i get one head and one tail?

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