Probability

Outside a home, there is a 9-key keypad numbered 1 through 9. The correct four-digit code will open the garage door. The numbers can be repeated in the code. (a) How many codes are possible? (b) What is the probability of entering the correct code on the first try, assuming that the owner doesn't remember the code? (a) The number of possible codes is (Type an integer or fraction. Simplify your answer.) (b) The probability that the correct code is given on the first try, assuming that the owner doesn't remember it is (Type an integer or fraction. Simplify your answer.)