Answer:
16/21
Explanation:
We need to first find the probability that we get a blue marble, then the probability that we get a red marble, and then add those two probabilities together.
Probability is essentially just (# times specific event can occur) / (# times a general event will occur).
Getting a Blue Marble:
The specific event here is getting a blue marble. Because there are 88 blue marbles, the number of specific events is 88. The general event is choosing any marble. There are a total of 88 + 55 + 88 = 231 marbles, so the number of times the general event occurs is 231.
Our probability is thus 88/231.
Getting a Red Marble:
The specific event now is getting a red marble. Because there are 88 red marbles, the number of specific events is 88. The general event is choosing any marble. There are a total of 231 marbles, so the number of times the general event occurs is 231.
Our probability is once again 88/231.
Now, add up these probabilities:
88/231 + 88/231 = 176/231 = 16/21
The answer in simplest form is thus 16/21.