SOLUTION: Along a stretch of road, two intersections have traffic lights. Having a red or a green light for the first intersection is equally likely. Having a red light at the second interse
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Question 1140037: Along a stretch of road, two intersections have traffic lights. Having a red or a green light for the first intersection is equally likely. Having a red light at the second intersection is twice as likely as a green light, if the traffic light is red at the first intersection. What is the probability of having a red light at the first intersection and a green light at the second intersection? Answer by ikleyn(52772) (Show Source):
From the condition,
- the probabilities to have G or R at the first intersection are each equal to ;
- if there is R at the first intersection, then the probability to have R at the second intersection is ,
while the probability to have G at the second intersection is .
From it, the probability under the question is
= . ANSWER
