To my understanding, unless the question type explicitly asks you to 'find the conclusion or what can be inferred from the passage' , both the above question types may not necessarily require you to find just the conclusion. In fact, there are some passages that may contain more than 1 conclusion and for 'main point questions' the correct answer would be a statement made typing up both the conclusions into 1 point. If you identify 2 conclusions and see 2 answer choices each containing one of the 2 conclusions, you are setting yourself up for disaster if you disregard the choice that may not explicitly state the conclusions but may subtly indicate an outcome of tying the 2 conclusions together while staying within the scope of the argument.
A must be true question type is one where the correct answer may be a hidden action (NOT an assumption) that was needed for the author to draw his conclusion.
An easy example:
Potatoes,in XYZ city, are only grown from the Beginning of July to the middle of August and spoil within a week of their harvest. To make my special ABC pie , fresh potatoes are an absolute must. The ABC pie i bought to my pot luck yesterday was a big success.
Question: If the author's pie was a success, which of the following must be true?
Here the correct answer could be something like : The author's potluck was held in the first week of August
Must be true questions, in most cases, already contain a conclusion and ask you to draw something that may be subtly stated in the argument but not blatantly tied to the conclusion. In the example i provided above, to find a must be true answer, you have to join the dots i.e. because potatoes are grown only from July - mid august and spoil within a week of there harvest AND because , for the author to make her pie, FRESH potatoes are a must AND because the author has baked a pie for her potluck, it must be true that the potluck was held in the time frame of the potato harvest because the author has to use fresh potatoes to bake her pie and the potatoes would spoil if she kept the pie for more than a week.
The conclusion here was that the author's ABC pie was a resounding success but if you see that in the answer choice , it would most certainly be wrong because we already know that this is true as per the question stem.
A main point question is a little more confusing. I had raised this point in a recent post so let me copy paste the same:
"As per my understanding, there is a fine line between Main point and conclusion. Conclusion could be a decision that one can come to after tying up 3 premises together whereas, with main points, the answer is supposed to encapsulate the entire argument.
Take for example Reading Comp. If a question asks you what the main point of the passage is, you wouldn't pick a decision that the author makes in the last line of the 3rd paragraph rather, you would look for an answer that contains a pattern shared by all 3 paragraphs"
Here an example:
Aspirin reduces the risk of heart attacks in people! In a study of previous heart attack sufferers, 85% of those who took a one aspirin a day did not suffer a second heart attack over the course of the study whereas, 80% of those who did not take any aspirin suffered another heart attack. However people should be careful about the amount of aspirin they ingest as the study also showed that, of the participants who took more than one aspirin a day, 100% of them suffered a seizure.
There are 2 conclusions to be drawn here:
1) Aspirin reduces the risk of heart attacks
2) Taking to much aspirin causes seizures
You may see both these choices in a question asking you for the main point but neither will be correct if there is a third answer choice that goes along the lines of:
People at a risk of suffering a heart attack should take no more than 1 aspirin a day.
This is the main point of the argument. Not the conclusion but after typing up all the premises in the argument, this can be concluded by us to be the main point.
Hope this helps.
