Solutions:
The first statement only tells us the number of people registered and doesn't give us any information on how many people who didn't attend seminar on first day attended on the second day therefore First statement is not sufficient to answer the question.
Second statement tells us that 80% of the total registered attendees attended the seminar on the second day but it doesn't tell us how many attended on the first day and how many of them attended on both the days therefore we can't figure out what percentage of attendees didn't attend seminar on either day therefore second statement is not sufficient to answer the question.
After combining the two statements, there are two extreme scenarios
First, that all the attendees on the second day had already attended seminar on first day as well therefore 10% attendees didn't attend seminar on either day
Second, that 70 percent of total attendees attended on both days and therefore each attendee attended the seminar on at-least one day and leaving none NOT attending on either day.
Inconsistent solution therefore right option choice is option E
2 day Seminar
This topic has expert replies
Source: Beat The GMAT — Data Sufficiency |
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GMATinsight
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Hi gdshamain,
Certain DS questions start off "thin", meaning that there is not much information (or clearly not enough information) to answer the given question. It's in the last couple of "steps" that you have to put in the real work.
Here, we're told that at a 2-day seminar, 90% of those registered attended the seminar on the 1st day. We're asked what percent of those registered did NOT ATTEND on either day.
Fact 1: Total registered = 1,000 people
This tells us that 900 people attend on the 1st day (and 100 did not), but it does not tell us anything about the 2nd day.
Fact 1 is INSUFFICIENT
Fact 2: Of those registered, 80% attended on the 2nd day.
Wth the information offered in the prompt, there are some possibilities to consider:
1) It's possible all 80% of the 2nd day attendees also attended on the 1st day; this means that 10% did not attend either day.
2) It's possible that NOT all 80% of the 2nd day attendees also attended on the 1st day; this means that some percent OTHER THAN 10% did not attend either day.
Fact 2 is INSUFFICIENT.
Combined, we run into the same problem that we did in Fact 2: even though we know that there were 1000 people registered, we DON'T KNOW how many of the 2nd day attendees attended on the 1st day.
Combined, INSUFFICIENT.
Final Answer: E
GMAT assassins aren't born, they're made,
Rich
Certain DS questions start off "thin", meaning that there is not much information (or clearly not enough information) to answer the given question. It's in the last couple of "steps" that you have to put in the real work.
Here, we're told that at a 2-day seminar, 90% of those registered attended the seminar on the 1st day. We're asked what percent of those registered did NOT ATTEND on either day.
Fact 1: Total registered = 1,000 people
This tells us that 900 people attend on the 1st day (and 100 did not), but it does not tell us anything about the 2nd day.
Fact 1 is INSUFFICIENT
Fact 2: Of those registered, 80% attended on the 2nd day.
Wth the information offered in the prompt, there are some possibilities to consider:
1) It's possible all 80% of the 2nd day attendees also attended on the 1st day; this means that 10% did not attend either day.
2) It's possible that NOT all 80% of the 2nd day attendees also attended on the 1st day; this means that some percent OTHER THAN 10% did not attend either day.
Fact 2 is INSUFFICIENT.
Combined, we run into the same problem that we did in Fact 2: even though we know that there were 1000 people registered, we DON'T KNOW how many of the 2nd day attendees attended on the 1st day.
Combined, INSUFFICIENT.
Final Answer: E
GMAT assassins aren't born, they're made,
Rich
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sanju09
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We are supplied percent, and we are asked a percent only. We really don't need any number as total or anything in the group formula, where 100 works good as total.gdshamain wrote:Thanks in advance.
Statement (1) is therefore irrelevant and insufficient.
The group formula for a group of two is:
Total = First + Second - Both + Neither, and we've to answer the 'Neither' part of it.
Statement (2) helps us fill the formula as:
100 = 90 + 80 - Both + Neither, or Both - Neither = 70, which gives the minimum possibility for 'Both' as 70, and leaves a zero for the 'Neither', and the maximum possibility for 'Both' as 80, and leaves a 10 for the 'Neither'. Hence insufficient.
Combining won't help us any as an irrelevant statement automatically eliminates (C) choice on DS.
Choose [spoiler](E)[/spoiler].
The mind is everything. What you think you become. -Lord Buddha
Sanjeev K Saxena
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Sanjeev K Saxena
Quantitative Instructor
The Princeton Review - Manya Abroad
Lucknow-226001
www.manyagroup.com
