1. An urn contains four red marbles and three green marbles. One marble is removed, its color noted, and the marble is not replaced. A second marble is removed and its color noted.
(a) What is the probability that both marbles are red? Green?
(b) What is the probability that exactly one marble is red?
2. A factory that produces three-dimensional models has two 3D printers. Printer A is very reliable and produces 200 models every week. Printer B is a little less reliable and produces 201 models on 99% of the weeks, but breaks down and produces 0 models the rest of the weeks.
(a) In a random week, what is the probability that Printer B produces more models that Printer A?
(b) After 200 weeks have elapsed, what it the probability that Printer B has produced more total models than Printer A? Printer A will have produced 40,000 models. If Printer B breaks down at least once, it will have produced fewer models?