You have two cards. One is red on both sides, and the other is red on one side and black on the other. After shuffling the cards behind your back, you select one of them at random and place it on your desk with your hand covering it. Upon lifting your hand, you observe that the face showing is red.
a. What is the probability that the other side is red?
b. Provide an intuitive explanation for the result in part (a).