As a check on the quality of an electronics assembly line, a quality control engineer gives a pass/fail test to parts coming off the end of the assembly line until she is able to collect 12 good parts. She then reports the number z, which is the number of parts she had to test to get the 12 good ones? (a) What kind of random variable is z? (b) How high must the probability of a part passing be in order for her to have a 35% chance of getting 12 good parts from the first 12 she tests