7.A boat's speedometer reads 35 miles per hour (which is relative to the water) and sets course due west (90° from due north). If the river is moving 12 miles per hour due north, what is the
resultant (actual) velocity of the boat

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?