pr.probability - Porbability of selecting balls from boxes

Well, this looks more like someone trying to get their homework done, but for the first part:

$ p = 0.2 * frac{3}{3+7} + 0.2 * frac{5}{5+5} + 0.6 * frac{2}{2+8}$

$ p = 0.06 + 0.10 + 0.12 $

$ p = 0.28 $

Showed the work for you too.

So if the probability that a chosen ball is red is 28%, then the probability that a chosen ball is green is 72%.

So what is {probability that chosen ball came from B3 | chosen ball is green}? Look up conditional probability, look up bayesian, etc.

$ p_g = 0.2 * frac{7}{3+7} + 0.2 * frac{5}{5+5} + 0.6 * frac{8}{2+8}$

$ p_g = 0.14 + 0.10 + 0.48 $

$ p_g = 0.72 $

{ $p_g3$ | green ball} = (picked from box 3 and green) / (picked green)

= 0.48 / 0.72

= 2 /3

Please do your homework yourself.
Showed the work for you too.