megancdrake
How did you know to make neither 0? I've had questions where I assumed neither was 0 and was wrong so curious if there's a helpful tip for that. Because the question says "6,000 subscribe to Herald OR Clarion" that led me to think that "both" and "neither" are not included in the 6,000. Thank you!
The set theory or Venn diagram has two important terms - AND , OR used in the question.
AND - denotes the
intersection part. For example , I would like to have dish A AND dish B.
Focusing on the Overlapping part alone.

While,
OR - denotes the
union regions.
A only, B Only, and Both A and B.

The question mentions, In Libreville , 6000 subscribe to either Herald OR Clarion.
I am running my thought process, I believe you might get some insights from this.
The first thing, it’s a two set Venn diagram. (Herald and clarion). It contains Herald only, Clarion Only, Intersection between Herald and Clarion, and the neither part.
Secondly, Be sure, that we are not given the total population in this problem.
Then, the question mentions 6000 subscribers belong to either Herald
OR Clarion.
Amongst, the population given, this 6000 fall into one of these two categories or might be in their intersection part. This is the first instance where u can say, NEITHER is excluded from the 6000.
This boils down to a critical point- neither vs total population values ?
We can definitely say, the 6000 is within the total population. However, Until unless, we have concrete information about neither or the total population. We cannot, for time being conclusively say neither is zero.
Now, If it has been a quant question, with this data in hand, proceeding further might be impossible. As we have two unknowns - neither and total population.
Being a data sufficiency question, we need to act within the constraints provided by the question stem. As the question directs us to find the intersection part.
We have for the convenience of solving this question,
assumed neither to be zero. So, that it brings the total population as 6000, providing a full picture to navigate the statements.
If in case, they have mentioned the total population is 8000, then now u can concretely say, the extra 2000 falls into the neither category. As, Herald OR clarion denotes the UNION of the sets.
Moreover, The sum of all elements in a set, should add to Total population .
If in case, the question demands us to work with neither, then specific inputs will definitely be in place to address it.
Hope this addresses your concerns.
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