Verbal questions and topics from the Official Guide and Verbal Review books.
mridul12
 
 

OG - CR - #77

by mridul12 Fri Aug 03, 2007 1:24 am

Dan,

I like your concept of Negation Test to verify the answer in CR questions in which you have to find "Assumption". Thanks.

I have following two questions for you.

Q 1 ) I still get confuse whether between the Questions of Assumption Type : Eliminate Alternate Path to the same end and Assumption Type: Alternate Model of Causation. They tend to overlap in several question. Any technique or clue that might be useful here .


Q 2) from OG 11th Edition, Problem 77 ( Page 490)

Roland: The alarming fact is that 90 percent of the people in this country now report that they know someone who is unemployed.

Sharon: But a normal, moderate level of unemployment is 5 percent, with one out of 20 workers unemployed. So at any given time if a person knows approx. 50 workers, one or more will very likely be unemployed.

Sharon's argument relies on the assumption that _________ .

A) normal levels of unemployments are rarely exceeded
b) unemployment is not normally concentrated in geographically isolated segments of populations
c) the number of people who each know someone who is unemployed is always higher than 90 percent of the population
d) Roland is not consciously distorting the statistics he presents
e) knowledge that a personal acquaintance is unemployed generates more fear of losing one's job than does knowledge of unemployment statistics.

What is the ASSUMPTION TYPE here .
How do you use NEGATION TEST here.

Regards,

[/b]
dbernst
ManhattanGMAT Staff
 
Posts: 300
Joined: Mon May 09, 2005 9:03 am
 

by dbernst Fri Aug 03, 2007 11:24 am

mridul12

The questions you raise are interesting. I too become confused if, while taking an actual GMAT, I consciously attempt to identify the assumption type of a particular question. Instead, I use the identification of assumption types as training tool. By identifying particular assumption types as I REVIEW my homework or practice tests, I become more familiar with the types of answer choices that are often correct on assumption questions. Moreover, I become better aware of the methods that the test makers use to intentionally push me away from the best answer (i.e. those dastardly "attractive distractors").

In the question at hand, Sharon is not surprised by Roland's information that 90 percent of the people in this country now report that they know someone who is unemployed. In fact, Sharon concludes this fact makes sense since, given that a person knows 50 workers, and the unemployment rate is 5%, he/she should know "one or more" unemployed workers (as 5% of 50 = 2.5).

BEFORE looking at the answer choices, let's consider possible assumptions:

In this case, Sharon is assuming that all people know a sample population of workers that are equally likely to suffer 5% unemployment. If this were not the case, Sharon's conclusion crumbles.

As answer choice B is a restatement of the assumption I recognized, it is the best answer. However, I will use the negation test with choice B to ensure that I have not been careless.

Original b) unemployment is not normally concentrated in geographically isolated segments of populations

Negated b) unemployment IS normally concentrated in geographically isolated segments of population

If unemployment were concentrated in geographically isolated segments of populations, then randomly selected individuals would not have an equivalent chance of knowing an unemployed person. Instead, based on geographic factors, some individuals would be much more likely to know unemployed workers than would other individuals. In this case, Sharon's conclusion crumbles.

The correct answer is B.

ps. I would identify this as a "fill in the logic gap" assumption type. The unstated assumption helps explain how we get from the premises (5% unemployment, 90% people know someone unemployed) to the conclusion (a person who knows 50 workers will most likely know at least one unemployed worker)

Hope that helps!

-dan



Roland: The alarming fact is that 90 percent of the people in this country now report that they know someone who is unemployed.

Sharon: But a normal, moderate level of unemployment is 5 percent, with one out of 20 workers unemployed. So at any given time if a person knows approx. 50 workers, one or more will very likely be unemployed.

Sharon's argument relies on the assumption that _________ .

A) normal levels of unemployments are rarely exceeded
b) unemployment is not normally concentrated in geographically isolated segments of populations
c) the number of people who each know someone who is unemployed is always higher than 90 percent of the population
d) Roland is not consciously distorting the statistics he presents
e) knowledge that a personal acquaintance is unemployed generates more fear of losing one's job than does knowledge of unemployment statistics.

What is the ASSUMPTION TYPE here .
How do you use NEGATION TEST here.