Commuting to school: A student, who lives off campus, always leaves her apartment at the same time and takes the same route. She feels as though she is constantly stopping at red lights, so she starts to collect some data. To get to school, she must pass through four traffic lights and stops at each one that is red. After collecting data for several months, she developed the following probability model for the number of red lights she hits. X = # of red lights 0 1 2 3 4
Probability 0.05 0.25 0.35 0.15 0.20
Given that she will hit at least one red light, what is the probability that she will actually hit at least three red lights during her commute?
A 0.75
B 0.3684
C 0.1579
D 0.35
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