The Alphabet

GRE Big Book Critical Reasoning Test 21

Jimmy Wang
07/11/2024

GRE Critical Reasoning

Directions

Critical Reasoning questions test the ability to understand, analyze, and evaluate arguments. Some of the abilities tested by specific questions include identifying the roles played by specific phrases or sentences in an argument, recognizing the point of an argument, recognizing assumptions on which an argument is based" drawing conclusions and forming hypotheses, identifying methods of argumentation, evaluating arguments and counter-arguments, and analyzing evidence.

Each of the Critical Reasoning questions is based on a short argument, a set of statements, or a plan of action. For each question, select the best answer of the choices given.

The presence of microorganisms that produce a toxin causes seawater to turn brownish red, a phenomenon known as a red tide. Sea otters do not feed in areas where clams, their main source of food, have become contaminated with this toxin. According to a proposed explanation of the otters’ behavior, the otters sample the clams in a potential feeding area and can taste any toxin in them.

#1

Which of the following, if true, would most strongly indicate that the hypothesis described in the last sentence of the passage is not correct?

Although very small amounts of the toxin produced during a red tide are not harmful, large doses can be fatal to animals the size of sea otters.

The presence of sea otters in a given area has a significant effect on which other marine organisms are to be found in that area.

In some of the areas where red tides occur, neither clams nor sea otters are indigenous species.

When seawater in an area unaffected by red tide is artificially dyed brownish red, sea otters do not feed on the clams in that area.

If the clams in a given area are contaminated with toxins, sea otters move to other areas in search of food.

An acre of average farmland produces only about 400 pounds of grain amaranth, as against 2,400 pounds per acre, or six times as much, for wheat. It follows that whenever the grain-amaranth price is projected to be more than six times the projected price of wheat, farmers wishing to maximize profits will grow grain amaranth rather than wheat.

#2

The argument above is based on which of the following assumptions?

Prices of grain crops can change faster than farmers can change the acreage devoted to various grain crops.

An acre’s worth of grain amaranth is no more expensive to grow and bring to market than an acre’s worth of wheat.

There is no crop that produces a higher yield in terms of pounds harvested per acre than wheat.

By choosing which crops to grow, farmers can exert a significant influence on the prices of those crops.

Farmers are no less motivated by the desire to maximize profits than are other occupational groups.

Most road repairs require more time and money than is budgeted, but last summer’s nighttime repairs of Highway 93 and similar roads required no more time or money than had been budgeted. Therefore, making summer repairs to major roads at night would save both time and money.

#3

Which of the following, if true, most strongly supports the conclusion drawn above?

Road repair crews that work at night mark their work sites with bright flashing lights in addition to the orange cones they use during the daytime.

Road workers who are willing to work at night have an easier time finding jobs, since most people would rather work in the daytime.

The budget for the repairs to Highway 93 was generous enough to make it unlikely that it would be exceeded.

Asphalt used in road repair tends to expand in warmer temperatures and contract in cooler temperatures.

The smaller number of cars on the roads at night and more comfortable nighttime temperatures allow road workers to work more quickly.

If oven cleaner is added to household the mixture emits chlorine gas. A mixture of bathtub cleanser and household bleach also emits chlorine gas. I f ordinary soap is added to household bleach, no gases are emitted. When an unidentified cleaning agent was added to household bleach, no chlorine gas was emitted.

#4

If the statements above are all true, which of the following can be determined conclusively on the basis of them about the unidentified cleaning agent?

It contained ordinary soap and neither oven cleaner nor bathtub cleanser.

It was neither oven cleaner nor bathtub cleanser.

It contained ordinary soap and either oven cleaner or bathtub cleanser.

It was ordinary soap.

It was either oven cleaner or bathtub cleanser.

Cars fueled by methanol have a much lower level of emissions of pollutants such as carbon monoxide and environmentally harmful hydrocarbons than gasoline-fueled cars do. Methanol fuel does produce somewhat higher formaldehyde emissions than gasoline does. Nevertheless, a methanol-powered car actually produces less atmospheric formaldehyde pollution than a comparable gasoline-powered car, because __________.

#5

Which of the following, if true, provides the most logical completion of the passage below?

gasoline-powered cars are required by United States law to be equipped with catalytic converters that reduce emissions of many pollutants

measuring a car’s emissions is generally an accurate method of assessing that car’s contribution to atmospheric pollution

the technical difficulties involved in mass- producing methanol-powered cars will prevent them from seriously competing with gasoline-powered cars for several years

compared to carbon monoxide and some hydrocarbons produced by gasoline-powered cars, formaldehyde pollution is not a serious threat to the environment

most formaldehyde pollution generated by gasoline-powered cars results from the photo- chemical conversion of hydrocarbon emis- sions into formaldehyde in the atmosphere

Until recently experts believed that environment, not genetics, largely determines human personality. A new study, however, has shown that there is more similarity in personality between identical twins raised together than between nonidentical twins raised together. The study concluded that genetics, therefore, does play an important role in determining personality.

#6

Which of the following, if found to be true, would cast the most doubt on the study's conclusion?

No matter how twins behave, parents treat identical twins in ways that tend to elicit similar personality traits but do not treat nonidentical twins in such ways.

Neither identical nor nonidentical twins are likely to display drastic changes in their individual personalities as they grow up.

Birth parents and their identical twin children tend to become more similar to each other in personality over time, but adoptive parents and their identical twin children do not.

Parents of both identical and nonidentical twins have long claimed that their children, from early infanthood, had definite and well-established personality traits.

Identical twins raised separately in different adoptive families are usually more siinilar in personality than are nonidentical twins raised separately in different adoptive families.