Arational number is defined as a ratio of two integers. given that a ratio is a fraction, how can a decimal be a rational number?

What is the frequency of the sinusoidal graph?

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

1yd 1 ft = 1 1/12 1 1/3 1 1/2 1 1/6