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morya003
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BR

With the Set A and Set B stuff, we have to be very careful about wording.

If we add (Set A only) and (Set B only) with the (neither) group, then the group (both A & B) hasn't been counted at all, because those folks are not included in (Set A only) or (Set B only). Therefore, in that case, we have to add all four:

Total = (Set A only) + (Set B only) + (neither) + (both A & B)

If you think about it, those are the four separate regions on an standard Venn Diagram.

It's very different if we add (everyone in A) and (everyone in B), because each one of those sets includes the people in (both A & B). When we add those first two, the group (both A & B) gets counted twice, and we have to subtract the overlap.

Total = (everyone in A) + (everyone in B) + (neither) - (both A & B)

You see, you were simply writing (Set A) + (Set B), without making the distinction of (Set A only) vs. (everyone in Set A).

The OG solution is correct, because they had specified (Set A only) and (Set B only) and solved accordingly, but you were interpreting those as (everyone in Set A) and (everyone in Set B). Does that make sense?

Please let me know if you have any more questions.

Mike :)
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Hi Mike
Thanks ...but am still not entirely sure...because even in the OG they give 2 circles

1st circle 60
2nd circle 3x
intersection x

if you add all the above 3 as per OG then you are counting brand A and B twice

If you want to add then they should be added as follows

(60-x)+x+(3x-x)=120
60 + 2x = 120
2x = 60
x = 30
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BR

I'm at home right now, and I don't have the OG with me, but according to your first post, the original text was:

A marketing firm determined that, of 200 households surveyed, 80 used neither Brand A nor Brand B soap, 60 used only Brand A soap, and for every household that used both brands of soap, 3 used only Brand B soap. How many of the 200 households surveyed used both brands of soap?

Again, the crucial part is the wording. The 60 does not represent everyone who uses Brand A; it represents the folks who use "only Brand A." By definition, that excludes and does not count the people who use both Brand A and Brand B.

The question would be very very different if they said: "60 people use Brand A." That would imply that 60 is the number of everyone who uses Brand A, both the folks who use only Brand A and the folks who use both Brand A and Brand B. Often, on the GMAT, these set questions are set up that way, and when they give a number, it's a number that includes the "only" people and the "both" people.

Here, because of the precise wording, we know it's a different kind of question -- the 60 is "only Brand A", and include no overlap, no part of the "both" people.

Similarly, the 3x that we use for Brand B is technically for the folks who use "only Brand B" --- again, that contains no overlap and does not include any of the folks who use "both".

With the GMAT, you can rely on the wording to give you all the precision you need. I don't have the OG with me, so I can't see the diagram to which you are referring, but based on the wording of the question, I am going to say about that diagram:

= The 60 refers not to the whole circle but to the "lune" --- or whatever you want to call the piece of the circle left when you subtract the overlap. I attached a rough diagram to demonstrate this visually -- 60 is not the circle, but rather the lune.
= Similarly, the 3x refers not to the other circle, but again, to the "lune" on that side.
= x is the overlap, the part included in neither "lune"

Therefore, when you add 60 + x + 3x, there's absolute no overlap to be subtracted, because those are three mutually exclusive and non-overlapping conditions.

We know they are mutually exclusive and non-overlapping because the question text was precise in specifying "only Brand A" and "only Brand B."

Does this clear things up? Please let me know if you have any further questions.

Mike :)
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1% of degree = 1/100
So 1 anglet = 1/100 Degree
So, how many anglets = [fraction][/fraction]360/(1/100)... solving the same = 36000
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PareshGmat hi,

can you please explain the fraction part?

Thanks
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1% of 1 degree is 1 anglet
hence, 1 degree or 100% of 1 degree is 100 anglet.
Thus full-circle or 360 degree is 100*360 =36000 anglet ............Ans e
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