According to the National Science Foundation, during the Fall 2008 semester (the most recent data available) 30.13% of all science and engineering graduate students enrolled in doctorate granting colleges in the United States were temporary visa holders (www.nsf.gov/statistics/nsf11311/pdf/tab46.pdf). Assume that this percentage holds true for current such students. Suppose that two students from the aforementioned group are selected and their status (U.S. citizens/permanent residents or temporary visa holders) is observed. Draw a tree diagram for this problem using C to denote U.S. citizens/permanent residents and V to denote temporary visa holders. Find the probability that in this sample of two graduate students
a. at least one student is a temporary visa holder
b. both students are U.S. citizens/permanent residents