Given that
The Astros' probability of winning is 1/3.
The Cardinals' probability of winning is 1/6.
The Reds' probability of winning is 1/4.
The Cubs and the Pirates have the same probability.
Let x be the probability of Cubs and Pirates.
We know that the sum of all the probabilities is equal to 1.
Adding all the probabilities as follows.
Here LCM of 3,6, and 4 is 12, making the denominator 12.
Adding -3/4 on both sides, we get
Dividing by 2 on both sides, we get
Hence the Cubs' probability is 1/8, and the Pirates' probability is 1/8.
Hence the option 4th is correct.