Inferences

A statistical model predicts a city's electricity demand from the previous day's temperature, fitted as a straight line through some three thousand six hundred daily observations. Engineer Marisol Quijano notes that the model was fitted using data from a decade in which the city had almost no air conditioning, and that air conditioning is now installed in four households out of five. The relationship between temperature and demand in a city with widespread air conditioning is known to be different in kind, not merely in degree: past a threshold the curve bends sharply instead of rising steadily. She concludes that applying the model to the city today ______

Which choice most logically completes the text?

• A) requires only that the model be rescaled to the current population.
• B) is not justified by the data the model was built on. ✓
• C) will systematically underestimate demand on cold days.
• D) shows that temperature no longer affects electricity demand.

Why: The model was fitted on a decade when the city had almost no air conditioning, four households in five now have it, and the temperature-demand relationship in an air-conditioned city is different in kind, not merely in degree, so applying the model today "is not justified by the data the model was built on." Answering that it "requires only that the model be rescaled to the current population." offers a fix for a difference of degree, which the text explicitly rules out, and population is not what changed. Answering that it "will systematically underestimate demand on cold days." names a direction and a season the passage never addresses; the curve bends past a heat threshold, not on cold days. Answering that it "shows that temperature no longer affects electricity demand." reverses the point, since a sharply bending curve is a strong temperature effect, not the absence of one.

Brazil requires its citizens to vote, and those living abroad had long been able to cast a municipal ballot only by appearing in person at a consulate, sometimes in another country. Political scientist Diego Ferraro analyzed voter turnout in municipal elections in four mid-sized Brazilian cities before and after each introduced online absentee voting for residents living abroad. In every case, turnout from abroad rose substantially, in one city from about a tenth of registered emigrants to nearly a third, while turnout from within each city, where most voters have a polling station within walking distance, remained unchanged. Ferraro concludes that ______

Which choice most logically completes the text?

• A) voter turnout from abroad increased because residents living abroad were more interested in municipal elections.
• B) online absentee voting primarily affects turnout among voters for whom traditional access is most costly. ✓
• C) traditional voting methods are less convenient for citizens living within Brazilian cities.
• D) online voting systems reduce turnout among voters who prefer to vote in person at polling locations.

Why: Before the change, emigrants could vote only by appearing in person at a consulate, sometimes in another country, while voters at home usually had a polling station within walking distance. Turnout from abroad then rose substantially in all four cities while turnout inside them stayed unchanged, so online absentee voting primarily affects turnout among voters for whom traditional access is most costly. Interest was never measured, and what changed was the cost of voting rather than how much anyone cared, so the data do not show that voter turnout from abroad increased because residents living abroad were more interested in municipal elections. Voters inside the cities mostly had a station within walking distance, so it reverses the passage to say traditional voting methods are less convenient for citizens living within Brazilian cities. And in-city turnout held steady rather than dropping, so nothing supports the claim that online voting systems reduce turnout among voters who prefer to vote in person at polling locations.

To predict how a new roofing membrane will age, manufacturers heat samples to eighty degrees, on the principle that heat speeds the same chemistry sunlight drives. Materials scientist Bruno Lindgren found that above sixty degrees the membrane's plasticizer migrates to the surface, a process that does not occur at rooftop temperatures and that protects the material underneath. Membranes in service reach fifty-five degrees on the hottest afternoons and spend most of the year far below that. Samples held at eighty degrees outlasted samples held at fifty. Lindgren argues that the accelerated test's result ______

Which choice most logically completes the text?

• A) shows the membrane will last longer on hot roofs than on cool ones.
• B) proves that heat does not speed the chemistry sunlight drives.
• C) reflects a protective process that rooftop conditions never trigger. ✓
• D) understates the membrane's true service life on an actual roof.

Why: Above sixty degrees the plasticizer migrates to the surface and shields the material underneath, but real roofs never reach even fifty-five degrees, so the extra durability the eighty-degree samples showed comes from a process rooftop membranes never experience. "shows the membrane will last longer on hot roofs than on cool ones." carries a laboratory artifact over to real roofs, where the migration that produced it never happens. "proves that heat does not speed the chemistry sunlight drives." rejects the general accelerated-aging principle, when Lindgren's objection is only about this particular test temperature. "understates the membrane's true service life on an actual roof." has the direction backwards, since the migration artifact inflates the eighty-degree result rather than hiding extra life a real roof would show.