Plz help me do this

Which representation has a constant of variation of -2.5

There are three bags: a (contains 2 white and 4 red balls), b (8 white, 4 red) and c (1 white 3 red). you select one ball at random from each bag, observe that exactly two are white, but forget which ball came from which bag. what is the probability that you selected a white ball from bag a?

Kira looked through online census information to determine the overage number of people living in the homes in her city what is true about kira's data collection?