Executive PrepLab · V2 · Practice 2

Inference, paradox, boldface roles

Executive PrepLab · Verbal · Critical Reasoning Inference · paradox · boldface roles

These three types work differently from the four in Block 1, and differently from each other.

Inference inverts the format: the passage is a set of facts rather than an argument, and the answer must follow with certainty rather than plausibly.

Paradox gives you two facts that appear to conflict and asks what makes both true at once.

Boldface asks about structure rather than content, and is the only type where knowing what the argument says is not enough.

Drills first, per type, because the drills for these three cannot be shared.

Layers 1–2

Inference

For each, write what must be true. If nothing follows, write nothing.

D1. All the specimens that fluoresced under ultraviolet light contained the

D2. Every applicant who was shortlisted had published in a peer-reviewed

D3. Some of the wells drilled after 1990 are contaminated. What follows about

D4. Most of the committee voted in favour. Everyone who voted in favour had

D5. No bird in the collection from the northern range has a red crest. Some

D6. If the tide gauge is functioning, it transmits a reading every six

D7. If the tide gauge is functioning, it transmits a reading every six

D8. Every document in the archive has been digitised. Some digitised

	What follows
D1	No specimen lacking the mineral fluoresced. The contrapositive of the first statement. The second statement adds that the reverse does not hold
D2	They were not shortlisted. Contrapositive
D3	Nothing. Some about one group says nothing about another
D4	Most of the committee had read the report. The "most" carries through the universal
D5	Some birds in the collection are not from the northern range. The red-crested ones must come from elsewhere
D6	The gauge was not functioning at 0300. Denying the consequent — valid
D7	Nothing about the gauge. Affirming the consequent — invalid. Something else could transmit a reading
D8	The set of digitised documents is larger than the archive. A restatement, and restatements are the safest inferences there are

D6 and D7 are the pair to fix. Same conditional, opposite second premise, and only one of them yields a conclusion. Denying the consequent works; affirming it does not. The exam builds items on both, and the invalid one always appears as a tempting answer choice.

Inference 1

All of the pottery fragments recovered from the lower stratum were fired at temperatures above 900 degrees. Some fragments fired above 900 degrees were recovered from the upper stratum.

If the statements above are true, which of the following must also be true?

Contrapositive of the first statement: fired above 900 → from the lower stratum is not what it says; it says from the lower stratum → fired above 900. So not fired above 900 → not from the lower stratum. That is B.

A reverses the conditional and is contradicted by nothing but supported by nothing either. C is chronology the passage never mentions — a plausible archaeological assumption and not a stated fact. D invents a proportion. E invents a community.

Inference 2

Most of the region’s dairy farms keep fewer than fifty cows. All farms keeping fewer than fifty cows are exempt from the quarterly reporting requirement.

If the statements above are true, which of the following must also be true?

Chain two statements: most dairy farms have fewer than fifty cows, and all such farms are exempt. So most dairy farms are exempt.

B reverses the relationship between exempt farms and dairy farms. C assumes the exemption is the only route to not reporting — larger farms might be exempt for another reason. D sounds like a restatement and is not: it claims something about the composition of the exempt group, which the statements do not describe. E is unsupported.

Inference 3

If the tide gauge is functioning, it transmits a reading every six minutes. No reading was transmitted between 0200 and 0400 on Tuesday.

Which of the following can be properly concluded from the statements above?

Denying the consequent. Functioning → transmits; no transmission → not functioning. Valid and certain.

B and C are the two specific ways the gauge might have failed, and the passage supports neither over the other — this is the classic over-specification trap. D is about history. E contradicts the stated interval.

Inference 4

If a manuscript was produced in the abbey scriptorium, it uses the distinctive blue pigment prepared there. The newly acquired manuscript uses that pigment.

Which of the following must be true on the basis of the statements above?

Affirming the consequent: the pigment does not tell you the manuscript came from the scriptorium, because nothing rules out other users of the pigment. So A is out — and A is the answer most candidates choose.

D is the contrapositive of the given conditional, which is always true when the conditional is. It feels beside the point, which is precisely why it is safe: it adds nothing. B goes the other way and is equally unsupported. C and E are the extra premises that would make A work, which is a good sign they are not already given.

Inference 5

Every grant awarded by the foundation last year went to a project with at least two institutional partners. No project in the marine programme has more than one institutional partner.

If the statements above are true, which of the following must also be true?

Chain: grants required at least two partners; marine projects have at most one. So no marine project met the condition.

A adds a rule about eligibility rather than outcome — the projects may have been eligible and simply not awarded. C reverses the conditional. D invents a proportion. E is about the future.

Inference 6

Analysis of an Alpine ice core shows lead concentrations in the layers corresponding to the second century that are four times those of the preceding century. Lead smelting was practised on a substantial scale in the region during that period, and no other source known from the archaeological record could have produced concentrations of that magnitude.

The statements above most strongly support which of the following?

Note the stem: most strongly support, not must be true. That lowers the bar, and the correct answer takes advantage of it — attributable, at least in part is about as hedged as an option can be, and hedged is what survives here.

A generalises far beyond one region. C and E make claims about other periods the core layers described do not cover. D compares methods the passage never compares.

Inference 7

The proportion of the town’s residents who cycle to work has doubled since 2015. Over the same period, the proportion who drive has fallen by a fifth.

Which of the following must be true on the basis of the statements above?

Proportions are given; absolute numbers are not. C restates a proportion, so it is safe.

A and B both require knowing the population, and if the town shrank, a doubled proportion could mean the same number of cyclists or fewer. D compares two proportions whose starting values are unknown — cycling could have doubled from 2 percent to 4 percent while driving fell from 60 to 48. E is unsupported.

This is the item where a habit of thinking in absolute terms costs you. When a passage speaks only in proportions, only proportional conclusions are safe.

Inference 8

All the varieties in the seed bank that germinated after fifty years of cold storage have hard seed coats. Some hard-coated varieties in the bank did not germinate. Every variety collected from alpine sites has a hard seed coat.

If the statements above are true, which of the following must also be true?

Contrapositive of the first statement. The third statement about alpine varieties is genuinely irrelevant to what follows — it is there to see whether you will chain it into something.

A reverses the first statement and is contradicted by the second. C is the tempting one: alpine varieties are hard-coated, and some hard-coated varieties did not germinate, so surely some alpine ones did not. That does not follow — the non-germinating hard-coated varieties could all have come from elsewhere. D reverses the third statement. E is unsupported.

Layers 1–2

Paradox

For each, state the two facts that appear to conflict, then give one fact that would let both be true.

D1. A town installed speed cameras on its main road. Recorded speeding

D2. A clinic doubled the number of doctors on staff. Average waiting times for

D3. A river was cleaned of industrial discharge over a decade. Fish counts in

D4. National vaccination rates for a disease rose steadily. Reported cases of

D5. A museum abolished its admission charge. Revenue per visitor rose.

D6. A council introduced kerbside recycling collection. The tonnage sent to

	The two halves	A resolution
D1	More enforcement / more offences recorded	The cameras detect offences that were previously happening unseen. Recorded is doing the work
D2	More capacity / longer waits	Shorter waits attracted patients who had not previously sought appointments — capacity created demand
D3	Cleaner water / fewer fish	The discharge included nutrients that supported the food chain; removing it reduced the food supply
D4	More vaccination / more cases	Surveillance improved alongside the programme, so a higher proportion of cases is now detected and reported
D5	No admission charge / higher revenue per visitor	Revenue per visitor now comes from the shop and café, and visitors who paid nothing to enter spend more inside
D6	Recycling introduced / landfill unchanged	Total waste generated grew over the two years; recycling absorbed the growth without reducing the base

Four of the six turn on a word. Recorded offences, reported cases, revenue per visitor, tonnage sent — each is a measure rather than the underlying thing. When you see a paradox, read the two halves for what exactly is being counted. The hinge is usually there.

Paradox 1

A regional hospital doubled the number of consultants in its orthopaedic department. In the two years that followed, the average wait for an orthopaedic appointment increased by three weeks.

Which of the following, if true, most helps to explain the increase?

Induced demand. Expanded capacity changed referral behaviour, so the queue grew faster than the department’s ability to clear it. Both facts hold.

D deepens the paradox rather than resolving it — if waits rose everywhere, a doubling of consultants here should have made this hospital an exception. A, B and E offer friction but not enough: less experienced consultants and a building move would slow throughput somewhat, and neither explains a systematic three-week rise against doubled staffing.

Paradox 2

A river was cleared of industrial discharge over a decade of regulation. By the end of that decade, counts of the river’s principal fish species in its lower reaches had fallen by a third.

Which of the following, if true, most helps to explain the fall?

The discharge was feeding the ecosystem. Removing it removed the base of the food chain, so cleaner water and fewer fish are both true and causally connected.

B is a partial offset that does not explain the lower reaches. D and E are small additional pressures. A concerns timing without explaining direction.

Paradox 3

A national programme increased childhood vaccination coverage for a particular disease from 71 percent to 94 percent over five years. Reported cases of the disease rose by 40 percent over the same period.

Which of the following, if true, best explains the rise in reported cases?

A measurement change, and the hinge is reported. Mandatory laboratory confirmation and a new surveillance system mean a far higher proportion of existing cases now appears in the figures. Actual incidence may well have fallen.

A explains why coverage is imperfect but not a 40 percent rise. D and E concern who remains vulnerable, which would produce continuing cases, not more of them. C is irrelevant.

Paradox 4

A city introduced a deposit-return scheme for beverage containers. Two years later, the tonnage of household waste sent to landfill was unchanged.

Which of the following, if true, most helps to explain this result?

Two facts in one option, and both are needed. Containers were a tiny share of tonnage, so even complete capture would barely move the total; and total waste grew enough to absorb what the scheme diverted.

C, D and E are all leakages that explain partial ineffectiveness, not a completely unchanged total. A concerns the incentive’s strength.

Paradox 5

A publisher moved its academic journals from subscription access to open access, making all articles free to read. Citations of articles in those journals rose sharply, while the journals’ impact factors declined.

Which of the following, if true, best explains the two outcomes?

Total citations and impact factor measure different things: the first is a count, the second an average per article. Publishing many more articles that are individually little cited raises the total and lowers the average.

D is true of impact factors and does not explain a decline. A, C and E concern funding, readership and competitors, none of which touches the arithmetic relationship between a total and a mean.

Paradox 6

A supermarket chain replaced its loyalty-card discounts with lower shelf prices across the store. Total sales volume rose, but the number of customers visiting each week fell.

Which of the following, if true, most helps to explain these results?

Fewer visits, more per visit. Both facts hold because the measures are different: visits are a count of trips, volume is a count of goods.

A and C are background. D would affect margin, not visit frequency. E would tend to reduce both figures.

Paradox 7

A conservation body removed the invasive predator from an island to protect a colony of ground-nesting seabirds. Three years later the seabird colony was smaller than before the removal.

Which of the following, if true, most helps to explain the decline?

A trophic cascade. The predator was suppressing something worse for the seabirds, and removing it released the rodents.

D is the deepest-paradox option: if colonies declined everywhere, the removal looks even less effective. A and E are context. C would explain a single bad season, not a three-year decline.

Paradox 8

A manufacturer introduced a redesigned safety harness that testing showed to be substantially more effective at arresting falls. In the year after it was adopted across the industry, the rate of fall injuries among workers rose.

Which of the following, if true, most helps to explain the rise?

Risk compensation. The harness works, and the exposure rose faster than the protection improved. Both facts are true and the improvement is real.

E deepens the paradox. B is friction that might reduce compliance, but discomfort alone does not produce a rise. A and D are cost and training arrangements.

Layers 1–2

Boldface roles

For each, name the role of the boldfaced portion in one phrase. Use the vocabulary from V2.7: main conclusion, evidence supporting the conclusion, a position the argument opposes, a consideration the argument accepts, an explanatory hypothesis.

D1. The scheme has been widely praised for reducing waiting times. But the

D2. Rail electrification would cut emissions on the route by two thirds.

D3. Ornithologists have long assumed that the species migrates along the

D4. **The unusual mineral content of the water may explain the beer’s

D5. Critics argue that the levy has not reduced consumption. **Consumption

D6. The company attributes the productivity gain to its new scheduling

	Role
D1	A position the argument opposes — stated in order to be undermined
D2	A consideration the argument accepts — conceded, then set aside
D3	Evidence supporting the conclusion — the tracking data are what defeats the assumption
D4	An explanatory hypothesis — proposed, with support following
D5	Evidence the argument accepts but reinterprets — the fall is granted; its cause is denied
D6	Evidence offered by someone else, which the argument goes on to undercut — the company’s support, not the argument’s

D5 and D6 are the difficult pair. In both, the boldfaced portion is a true fact that the argument does not dispute — and in both, the argument denies what the fact was supposed to show. That distinction, accepting the fact while rejecting its significance, is what the harder items in this type are built on.

Boldface 1

Municipal composting programmes are defended on the ground that they reduce landfill volume. The savings in landfill capacity are substantial. But composting requires collection vehicles running the same routes as refuse trucks, and the emissions from those trips appear in no published assessment. Whether composting reduces a city’s total environmental burden remains unestablished.

In the argument, the two boldfaced portions play which of the following roles?

The first grants the strongest point of the position being answered — landfill savings are real — and then the argument sets it aside. The second is where the argument lands.

A is the near-twin and turns on one word: the argument does not reject the savings, it accepts them. That is the agree-or-oppose question from V2.7, and it decides the item. B reverses the roles. D misassigns the second portion.

Boldface 2

Ornithologists have long held that the species migrates along the coast. Tracking data from thirty tagged birds show a route inland over the mountains. Coastal sightings, on which the earlier view rested, are now understood to represent a small subpopulation. The coastal migration hypothesis cannot be sustained.

The two boldfaced portions play which of the following roles?

The tracking data are the argument’s own evidence, not a view it opposes. The opposed view is the long-held coastal assumption, which is not in bold.

D is the trap: it reads the first portion as belonging to the earlier view because that view is mentioned first. Position in the passage does not determine role. C makes the same error more directly. B and E misidentify the second portion.

Boldface 3

The company attributes last year’s productivity gain to its new scheduling software. Output per worker did rise by 14 percent in the year following installation. In the same year, however, the company replaced a third of its machine tools and retired its two oldest production lines. The software’s contribution to the gain has not been established.

The two boldfaced portions play which of the following roles?

The 14 percent rise is true and the argument does not dispute it — the word did signals acceptance. What the argument disputes is what the rise demonstrates.

A says the argument disputes the evidence, which it does not. C treats a fact as a position. D and E misread the second portion, which is a conclusion rather than an objection or a concession.

Boldface 4

Rail electrification on the northern route would cut emissions by two thirds. The capital cost of electrification is undeniably high. But the diesel fleet reaches the end of its service life within eight years and must be replaced regardless, and the incremental cost of electrifying over replacing is modest. The cost objection to electrification is weaker than it appears.

The two boldfaced portions play which of the following roles?

The high capital cost is an objection, granted openly with undeniably, then answered. The second portion is the conclusion.

B calls the cost evidence supporting the conclusion, which inverts it — the cost works against the argument’s position until it is answered. C and E reverse or misname the roles. D says the argument opposes the cost claim, but it concedes it.

Boldface 5

The unusual mineral content of the local water may account for the beer’s distinctive character. Brewers in the town have drawn from the same well for two centuries. Attempts to reproduce the beer elsewhere using identical malt, hops and yeast have consistently failed.

The two boldfaced portions play which of the following roles?

The first portion proposes an explanation, flagged by may account for. The second gives evidence for it: identical ingredients elsewhere fail to reproduce the result, which points at the water.

A treats a hedged hypothesis as a conclusion and misreads the second portion as an objection. E reverses the two. C and D misidentify both.

Boldface 6

Supporters of the sugar levy point to the 11 percent fall in consumption since it took effect. Consumption did indeed fall by that amount. But it had been falling at a comparable rate for six years before the levy was introduced, and the rate of decline did not change afterwards. The levy cannot be credited with the reduction.

The two boldfaced portions play which of the following roles?

The fall is accepted — did indeed fall — and what is rejected is the causal inference drawn from it by the supporters.

A is the near-twin: it says the argument disputes the evidence. It does not; it disputes what the evidence shows. That difference is the item. B calls a fact a position. D reads the fall as supporting the argument’s own conclusion, which it does not.

Boldface 7

A proposal to relocate the fish market has been justified on the ground that the present site floods. The site has flooded three times in the past decade. The proposed site, however, lies on the same floodplain and at a comparable elevation. Relocation would not address the problem it is intended to solve.

The two boldfaced portions play which of the following roles?

Three floods in a decade is granted — the argument accepts that the present site floods. Its conclusion is that relocation does not solve it, because the new site floods too.

B says the argument rejects the flooding evidence, which would make the whole argument incoherent. C and E reverse the roles. D calls a fact a hypothesis.

Boldface 8

Historians have generally attributed the town’s decline to the closure of the mine. The mine closed in 1873, and the population had fallen by a third within fifteen years. Parish registers, however, show that emigration from the town was already running above the regional average for two decades before the closure, and that the rate did not accelerate after it. The mine’s closure was a symptom of the town’s decline rather than its cause.

The two boldfaced portions play which of the following roles?

The first portion is the evidence the historians rely on: closure followed by population loss. The argument accepts both facts and rejects the causal reading, offering the parish registers against it. The second portion is its own conclusion.

D is the closest miss and fails on decisive — the argument accepts the facts and finds them precisely not decisive. A says the argument disputes them. B treats evidence as a position. E has both portions serving the same side.

Answer as many as you like, then check — it scores what you have answered so far, across all 24 items.

Layer 3

Diagnosis

Check your answers above, then read this. The pattern of what you missed matters more than how many.

If you missed	It means	Go back to
Inference 4 (chose A)	You affirm the consequent	D6, D7
Inference 1, 8	Contrapositive not automatic	D1, D2
Inference 2, 8 (chose C)	You chain statements that do not connect	D3, D5
Inference 6 (rejected the hedged option)	You treat weak language as too weak to be the answer	V2.5
Inference 7	You reason in absolute numbers from proportional premises	—
Paradox 1, 7 (chose D)	You choose the option that deepens the paradox	V2.6
Paradox 3, 4, 5, 6	You do not read for what is being counted	Drills D1, D4, D5, D6
Boldface 1, 6, 8	You conflate rejecting a fact with rejecting its significance	Drills D5, D6
Boldface 2	You assign roles by position in the passage	V2.7

The cross-cutting one. In inference, count how many of your wrong answers went further than the passage rather than not far enough. If most did, the fix is a single habit: for every option, ask how many steps it is from the text, and prefer the option that adds nothing. In this type, the boring answer is usually the right one.