Video Explanation

Text Explanation

Let's start with statement 1, which tells us that the probability of selecting a green chip is . This tells us that  of our chips are green. However, since statement 1 doesn't give us any information about the number of red chips, we don't have enough information to answer the question. 

To illustrate this, consider the following situations. 

First, imagine that we have one green chip, and two red chips. In this case, the probability of selecting a green chip is , and the probability of choosing a red or green chip is 1.  

Now imagine that we have one green chip, and two blue chips. In this case, the probability of selecting a green chip is , and the probability of choosing a red or green chip is also . 

As you can see, the probability of choosing a red or green chip is different in each of these two situations, even though the probability of choosing a green chip is  in both situations. So knowing that the probability of choosing a green chip is  not sufficient to answer the question, and statement 1 is insufficient. 

Now let's test statement 2, which tells us that the probability of selecting a blue chip is . From the complement rule, we know that the probability of NOT selecting a blue chip is . So the probability of NOT selecting a blue chip is .

Note that if we have a chip that is not blue, it must be either green or red. Thus, the probability of NOT choosing a blue chip, is the same as the probability of choosing a chip that is green or red. So therefore, the probability of choosing a chip that is green or red = . So statement 2 is sufficient, and B is the right answer.