We are learning about census, samples, bias, and population. i need help with these two questions.

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?

Which is the focus of a parabola with equation y2=4x

What is the value of x? assume that the line is tangent to the circle.