probability-answers

Solutions to the Sample Problems from Unit 11A: Probability
(click here to return to the problem set)
 * 1) If we take the probability that the cat is outdoors (40/60) and multiply that by the probability that the cat is black (40/60 * 25/60), you get a 27.7778% chance of seeing a black cat outdoors.
 * 2) 7/57
 * 3) 40*39*38*37*36=78960960
 * 4) Since you replace the CDs every day, they are all out of 10. (3/10) x (1/10) x (1/10) = 3/1000 or 0.3 %. If you didn't replace them, it would be (3/10) x (1/9) x (1/8) = 0.4167%.