nandinigaur wrote:
I thought i understood but then i saw the following qs:
In a consumer survey, 85% of those surveyed liked at least one of three products: 1, 2, and 3. 50% of those asked liked product 1, 30% liked product 2, and 20% liked product 3. If 5% of the people in the survey liked all three of the products, what percentage of the survey participants liked more than one of the three products?
in this how to know that we r being asked: people in exactly 2 grps + people in exactly 3 grps... no word is mentioned....
If the question wants to tell you the number of people who like 2 products but not all 3, it will say "30% people liked exactly two products."
Or "52% people liked only one of these products" when it wants to tell you that 52% people liked just a single product and did not like other two products and so on...
In this particular question, you are asked to find the number of people who liked more than one of the three products. This means you want the number of people who liked either 2 of the 3 products or all three products.
So you are looking for "people in exactly 2 grps + people in exactly 3 grps".
Note that you can calculate this in two ways:
Method 1:
people in exactly 2 grps + people in exactly 3 grps
Method 2:
people in 2 grps (including those in all three groups too) - 2* people in 3 grps (because they have been counted 3 times while counting people in 2 groups)
Check out this post for more on three overlapping sets:
http://www.veritasprep.com/blog/2012/09 ... ping-sets/ _________________
Karishma
Veritas Prep GMAT Instructor
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