6. In a metropolis, consecutive traffic lights are coordinated so that a driver who finds the first light green will find the second light also green with probability 0.75. Similarly, a driver who finds the first traffic light yellow or red will also find the second traffic light yellow or red with probability 0.75. Suppose that 50% of the time a traffic light is green.

Find the probability that a driver has to stop at least once for the red or yellow lights when passing through two consecutive traffic lights.