When conducting an observational study, it is important to choose a topic, select a variable, create a hypothesis, collect the data, and analyze the data for validity of the hypothesis. which additional step is also crucial to the success of the study?
observational study
nonrandomized study
sample survey
experimental study

A3-dimensional figure has a square base and 4 lateral faces that meet at a point. explain the difference between the cross sections when a slice is made perpendicular to the base through the vertex, and when a slice is made perpendicular to the base and not through the vertex

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

The following hormone had their receptors in the cell membrane except a-insulin b-tsh c-gh d- cortisol