Elaine is enrolled in a self-paced course that allows three attempts to pass an examination on the material. She skims the online reading and then takes the exam. On the first try she has probability 0.4 of passing. If she fails on the first try, her probability on the second try increases to 0.5 because she learned something from her first attempt. If she fails on two attempts, the probability of passing on a third attempt is 0.6.. She will stop as soon as she passes. The course rules force her to stop after three attempts in any case. Use your probability tree to calculate the probability that Elaine passes any of the three tests.