Here are the ten official questions which are discussed in detail in the Critical Reasoning - I module at the end of the Inference Questions section. Shout out in the comments section if you have any doubts in the explanations.
Inference Question No. 1
Comcorp Shipping Clerk: Last week, no shipments of building supplies were sent out on Friday. The five specially ordered shipments sent out last week were sent out on Thursday, and each of those specially ordered shipments consisted entirely of building supplies. Four shipments were sent to Truax Construction last week, none of which consisted of building supplies.
If the shipping clerk's statements are true, which of the following must also be true?
(A) All of Comcorp's shipments of building supplies last week were specially ordered.
(B) None of Comcorp's shipments sent on Friday of last week was sent to Truax Construction.
(C) None of the shipments sent by Comcorp to Truax Construction last week was specially ordered.
(D) None of Comcorp's shipments sent on Thursday of last week was sent to Truax Construction.
(E) All of Comcorp's shipments of building supplies last week were sent out on Thursday.
Inference Question No. 2
Telomerase is an enzyme that is produced only in cells that are actively dividing. For this reason it is generally absent from body tissues in adults. Bone marrow is an exception to this rule, however, since even in adults, bone marrow cells continually divide to replace old blood cells. Cancers are another exception, because their cells are rapidly dividing.
The information provided most strongly supports which of the following?
(A) Telomerase is the only enzyme that is present in cancerous cells but absent from cells that are not actively dividing.
(B) In children, the only body tissues from which telomerase is absent are those in which cells are not rapidly dividing.
(C) The presence of telomerase in bone marrow is no indication of bone marrow cancer.
(D) Cancer of the bone marrow develops more rapidly than cancer growing in any other kind of adult tissue.
(E) The level of telomerase production is always higher in cancerous tissue than in noncancerous tissue.
Inference Question No. 3
When a city experiences a sharp decline in population, the city's tax revenues, which pay for such city services as police protection and maintenance of water lines, also decrease. The area to be policed and the number and length of the water lines to be maintained, however, do not decrease. Attempting to make up the tax revenue lost by raising tax rates is not feasible, since higher tax rates would cause even more residents to leave.
The information given most strongly supports which of the following general claims?
(A) If, in a city with sharply declining population, police protection and water line maintenance do not deteriorate, some other service previously provided by the city will deteriorate or be eliminated.
(B) If a city's tax rates are held stable over a period of time, neither the population nor the levels of city services provided will tend to decline over that period.
(C) If a city's population declines sharply, police protection and water line maintenance are the services that deteriorate most immediately and most markedly.
(D) A city that suffers revenue losses because of a sharp decline in population can make up some of the lost tax revenue by raising tax rates, provided the city's tax rates are low in relation to those of other cities.
(E) A city that is losing residents because tax rates are perceived as too high by those residents can reverse this population trend by bringing its tax rates down to a more moderate level.
Inference Question No. 4
The total market value of real estate in Altonville has steadily declined over the past four years. This decline has meant that the overall figure on which the city’s property tax is based—the assessed value of that real estate—has also declined. The percentage of assessed value that was paid as property taxes to the city, however, did not change from year to year during this period.
The information above most strongly supports which of the following?
(A) The percentage of Altonville’s yearly revenue that comes from money collected in property taxes did not change over the past four years.
(B) The percentage of Altonville’s yearly revenue that comes from money collected in property taxes has declined steadily over the past four years.
(C) The amount of revenue that Altonville collected from property taxes was lower last year than it was four years ago.
(D) During the past four years, Altonville officials increased tax rates on other sources of revenue such as retail sales and business profits.
(E) Altonville will soon require property owners to pay a higher percentage of the assessed value of their property as property tax.
Inference Question No. 5
A medieval manuscript called L contains all eighteen extant tragedies by the Greek playwright Euripides. Of these, ten called the “select plays,” are accompanied in L by ancient commentaries and also appear in other medieval manuscripts; this group includes some of Euripides’ best-known works, including the Medea. The other eight, which appear only in L, are called "alphabeticals", because they appear in alphabetical order, without commentary. The Electra is one of the alphabetical.
Which of the following can be reliably concluded on the basis of the statements given?
(A) Only Euripides’ best-known works are accompanied by ancient commentaries in extant medieval manuscripts.
(B) The select plays are accompanied by ancient commentaries because they were the best known of Euripides’ works.
(C) No commentaries were written about Euripides’ Electra in ancient times.
(D) Euripides’s Medea never appears in medieval manuscripts unaccompanied by ancient commentary.
(E) Euripides’ Electra does not appear accompanied by a commentary in any extant medieval manuscript.
Inference Question No. 6
Fact: Asthma, a bronchial condition, is much less common ailment than hay fever, an allergic inflammation of the nasal passages.
Fact: Over 95 percent of people who have asthma also suffer from hay fever.
If the information given as facts above is true, which of the following must also be true?
(A) Hay fever is a prerequisite for the development of asthma.
(B) Asthma is a prerequisite for the development of hay fever.
(C) Those who have neither hay fever nor asthma comprise less than 5 percent of the total population.
(D) The number of people who have both of these ailments is greater than the number of people who have only one of them.
(E) The percentage of people suffering from hay fever who also have asthma is lower than 95 percent.
Inference Question No. 7
Whales originated in the freshwater lakes and rivers of ancient Asia about sixty million years ago. Not until about ten million years later did species of whales develop specialized kidneys enabling them to drink salt water. Although fossil evidence shows that some early whale species that lacked such kidneys sometimes swam in the Earth’s saltwater oceans, these species must have had to return frequently to freshwater rivers to drink.
Which of the following is most strongly supported by the information given?
(A) Fossils of whale species dating from between sixty million and fifty million years ago will not be found on continents that were at the time separated from ancient Asia by wide expanses of ocean.
(B) Among whale fossils that date from later than about fifty million years ago, none are fossils of whale species that drank only fresh water.
(C) Fossils of whale species that drank fresh water will not be found in close proximity to fossils of whale species that drank salt water.
(D) The earliest whales that drank salt water differed from fresh-water-drinking whales only in their possession of specialized kidneys.
(E) Between sixty million and fifty million years ago, the freshwater lakes and rivers in which whales originated were gradually invaded by salt water.
Inference Question No. 8
Parasitic wasps lay their eggs directly into the eggs of various host insects in exactly the right numbers for any suitable size of host egg. If they laid too many eggs in a host egg, the developing wasp larvae would compete with each other to the death for nutrients and space. If too few eggs were laid, portions of the host egg would decay, killing the wasp larvae.
Which of the following conclusions can properly be drawn from the information above?
(A) The size of the smallest host egg that a wasp could theoretically parasitize can be determined from the wasp's egg-laying behavior.
(B) Host insects lack any effective defenses against the form of predation practiced by parasitic wasps.
(C) Parasitic wasps learn from experience how many eggs to lay into the eggs of different host species.
(D) Failure to lay enough eggs would lead to the death of the developing wasp larvae more quickly than would laying too many eggs.
(E) Parasitic wasps use visual clues to calculate the size of a host egg.
Inference Question No. 9
Among people who experience migraine headaches, some experience what doctors call "common" migraines, whereas others experience "classical" migraines. Siblings and spouses of common migraine sufferers are themselves twice as likely as the general population to experience common migraines. Siblings of classical migraine sufferers are four times more likely than the general population to experience classical migraines, whereas spouses of classical migraine sufferers are no more likely than the general population to experience such headaches.
The information above provides the most support for which of the following hypotheses?
(A) Susceptibility to classical migraines is more dependent on hereditary factors than is susceptibility to common migraines.
(B) Unmarried adults are more likely to suffer from classical migraines than they are to suffer from common migraines.
(C) People who do not experience migraine headaches are unlikely to have spouses who are migraine headache sufferers.
(D) Children of people who suffer from common migraines are more likely than the general population to experience a common migraine.
(E) Between one-quarter and one-half of the general population suffer from either common or classical migraine headaches.
Inference Question No. 10
The quality of unrefined olive oil is not actually defined in terms of acidity, yet extensive tests have shown that the less free oleic acid an unrefined olive oil contains per liter, the higher its quality. The proportion of free oleic acid that an olive oil contains is an accurate measure of the oil’s acidity.
If the statements above are all true, which of the following conclusions is best supported by them?
(A) When an olive oil is refined, the concentration of oleic acid in the oil is reduced.
(B) The quality of an unrefined olive oil can be determined only by accurately measuring its acidity.
(C) If an unrefined olive oil is intermediate in acidity between two other unrefined olive oils, it will also be intermediate between them in quality.
(D) Free oleic acid is the only acid that unrefined olive oil contains.
(E) People who judge the quality of unrefined olive oils actually judge those oils by their acidity, which the judges can taste.
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