Find the number of ways of arranging the letters of the word COMPUTER if 1) the letters in the even numbered positions must remain the same.
2) the arrangement must end with TER.

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?