Carson drives to school the same way each day and there are two independent traffic lights on his trip to school. He knows that
there is a 30% chance that he will have to stop at the first light and an 80% chance that he will have to stop at the second light. What is the probability that he will NOT have to stop at either light? A: 14%
B: 24%
C: 50%
D: 80%
All you have to do is take the 30% chance of you HAVING to stop at the first light and find the chance that you won't have to stop at the first light, which is 70%, or .7. Then you take the chance of having to stop at the second light which is 80%, and find the probability of NOT having to stop there, which is 20%, or .2. Then you multiply the probabilities of not having to stop, which equals to .14.
The probability that he will not have to stop at the first light is 1 - 0.3 = 0.7. The probability that he will not have to stop at the second light is 1 - 0.8 = 0.2. The probability that he will not have to stop at either light is: The correct answer choice is A.
