GMAT Verbal › Common Logical Fallacies
UCLA Sociologist: Between 1962 and 2012, the marriage rate (that is the percentage of adult women over 16 who get married for the first time each year) fell from 110 marriages a year per 1,000 unmarried women to just 37, a stunning 66 percent decline. Given this trend, there will likely be no women getting married for the first time by 2050!
Which of the following, if true, exposes a flaw in the sociologist’s reasoning?
As far back as the 1950s, research has shown that adults who participate in over 30 minutes of aerobic exercise at least three times a week have a significantly lower prevalence of respiratory illness than those who do not. In recent years, studies have consistently confirmed these same statistics. It can be concluded, therefore, that regular aerobic exercise can be helpful in preventing respiratory illness.
Which of the following, if true, would most weaken the argument above?
Researchers have shown that older ants, which usually spend more time gathering nourishment for the colony, tend to have larger brains than do younger ants, which usually help nurture ant larvae in the colony. Since gathering nourishment requires greater cognitive skills than does nurturing larvae, it would appear that such gathering leads to the increased brain size of older ants.
Which of the following, if true, most seriously weakens the argument above?
Epidemiologist: The cancer death rate (number of deaths from cancer per 1,000 people) in the city of Maple Grove is 30% percent higher now than it was ten years ago. The corresponding increase in Fernland, where a major anti-smoking initiative was introduced a decade ago, is only 10%. These figures support the conclusion that residents of Maple Grove are more likely to die from cancer than residents of Fernland.
The epidemiologist’s conclusion is flawed because it fails to consider __________________
A recent study suggests that not eating genetically modified foods can lead to a decreased risk of type 2 diabetes and heart disease. The study based this conclusion on the fact that individuals who ate only non genetically modified foods developed these conditions at lower rates than did individuals who ate both genetically modified and not genetically modified foods and concluded that the decreased risk of both diseases must be as a result of the individuals’ dietary differences.
Which of the following, if true, would weaken the conclusion that eating only non genetically modified foods leads to a lower risk of heart disease and type 2 diabetes?
Many people believe that soccer players are the most well-known athletes on the planet, citing the fact that professional soccer is televised in more countries than any other sport. This belief is misplaced, however: according to a name recognition survey, Fabricio, the star of professional soccer's AC Camarillo, is less recognized than the best players on 20 different professional basketball teams.
Which of the following most strengthens the conclusion drawn above?
Public Safety Official: In 1998, our province's highway patrol arrested nearly 25,000 motorists for driving under the influence of alcohol. Over the past 20 years we have implemented a number of legal measures to increase penalties for driving under the influence and that have increased the number of law enforcement personnel patrolling for such offenses. This past year, even though our population has increased markedly since 1998, our province saw less than 18,000 arrests - a sure sign that these legal measures have been successful in preventing motorists from driving while under the influence.
Which of the following, if true, would most weaken the public safety official's claims?
A high school has found that, for each of the last 15 years, the average grade point average for members of the cross-country running teams has exceeded the average grade point average for the school as a whole. This phenomenon can most likely be attributed to the fact that long distance runners have so much time to think while running that they can essentially study as they run.
Which of the following most undermines the conclusion drawn above?