Quote:
During the American westward expansion, a certain city in the eastern U.S. saw about 250 of its citizens depart for the west, but perish before arriving in their destination cities. During the same time period, the city saw about 225 deaths of citizens who stayed in the city. Based on these totals, it can be concluded that it was not much more perilous to be a settler who left the eastern U.S. to settle the western U.S. than it was to be a citizen who remained in the east.
Which of the following tests would most clearly reveal the flaw in the conclusion drawn above?
A. Counting deaths among people who left to settle the west but returned to their cities of origination in addition to those who died during their trips westward
B. Calculating the difference between the number of deaths among westward settlers and the number of deaths among non-settlers, then expressing this number as a percentage of all deaths during the period
C. Differentiating between settlers' deaths by non-settlement-related causes and those caused by accidents, murders, and battles attributable to the settlement process
D. Comparing the death rates per hundred members of each group instead of comparing the numbers of deaths in each group
E. Comparing deaths due to natural causes in the city of origin to unnatural deaths of settlers who originated in those cities
KAPLAN OFFICIAL EXPLANATIONIdentify the Question Type:
This question is a Flaw question. It asks for the answer choice that would most clearly reveal the logical flaw in the conclusion.
Untangle the Stimulus:
The author concludes there was no increased risk in being a settler versus staying in the east.
As evidence, the author states that during the westward expansion, 250 people who left the east to settle in the west died before arriving at their destination; during the same period 225 people who choose to remain in the east also died.
In order for these statistics to be meaningful, the author must be assuming that the total number of people who stayed in the east was equivalent to the total number of people who went west to settle.
Predict the Answer:
The correct answer choice will reveal something that is not comparable between these two groups. For instance, it might show that the number of people who stayed in the east was far greater than the number of people who attempted to settle in the west.
Eliminate the Wrong Answer Choices:
(D) matches the prediction; knowing the percentage of people in each group who died would much more clearly reveal the flaw in the argument than knowing the absolute number of deaths in each group.
(A) is incorrect because the argument is only concerned with people who died in transit from east to west as compared to those who stayed in the city. Furthermore, the right answer needs to compare those who left to those who stayed, and (A) doesn't give any information about people who stayed.
(B) is an irrelevant comparison; the right answer needs to compare the groups to each other
The cause of death is irrelevant the argument, which is about the number of deaths, so (C) and (E) are incorrect.
TAKEAWAY: This is a classic “numbers vs. percentage” flaw, a type that appears often in flawed GMAT arguments.