How many cubes with side lengths of \dfrac12 \text{ cm}
2
1

cmstart fraction, 1, divided by, 2, end fraction, start text, space, c, m, end text does it take to fill the prism?

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?