A. the mean should be useful predicting future results
Variables are used to store information to be referenced and manipulated in a computer program. ... It is helpful to think of variables as containers that hold information. Their sole purpose is to label and store data in memory. This data can then be used throughout your program.
A. most cameras will let you see the shot you took for a second afterwards witch allows you to see errors like motion blur,focus,white balance and other things.