Ramina found the length of two pieces of ribbon to be 47.6 inches and 39.75 inches. which is an effective estimation strategy for finding the sum of the two lengths? round 39.75 to 30 and 47.6 to 40, then add. round 39.75 to 40 and 47.6 to 48, then add. add 47.6 and 39.75, then round the answer. subtract 39.75 from 47.6, then round the answer.

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