A lab specialist performs lab tests on samples in Hampton, Virginia. Depending on the type of test that is performed, the lab test can take 1, 2, 3, or 4 hours to complete. The 1, 2, and 3 hour lab tests occur at the same rate, but the 4 hour lab test occurs at twice the rate of any of the other lab tests. Develop a probability distribution for the duration of a lab test. What is the probability that a lab test will take 2 hours?