SAT inferences questions: how to answer them

Penguins cannot fly, but their wings are not useless. Penguins use their stiff, flipper-like wings to push themselves through the water at high speed when chasing fish. Penguins' wings, therefore, ______

When the museum surveyed visitors, those who had used the free audio guide spent, on average, twice as long in the galleries as those who had not. However, the audio guide was offered only at the main entrance, and visitors who came in through the side entrance, mostly people taking a shortcut to the café, rarely saw it. The survey results, therefore, ______

Historian Amira Saleh studied diaries kept by travelers crossing a mountain pass in the 1800s. Travelers who crossed in early autumn almost never mentioned danger, while those crossing in late autumn often described fear and hardship. Yet official records show that the number of deaths on the pass was roughly the same in both seasons. Saleh suggests that ______

Glass frogs have transparent skin on their undersides. Scientists recently discovered that when a glass frog sleeps, it hides nearly all of its red blood cells in its liver, which is covered by a reflective layer. When the frog wakes, the blood cells return to circulation and the frog becomes noticeably less transparent. Because the frogs sleep during the day on the undersides of leaves, these findings suggest that ______

Linguists have noticed that words for very common actions, such as 'go' and 'be', are often irregular in many languages, while rare verbs tend to follow regular patterns. One explanation is that irregular forms survive only if speakers hear them often enough to remember them; when a rarely used irregular verb is forgotten, speakers simply apply the regular pattern instead. If this explanation is correct, then over time ______

Ancient Egyptian builders used copper tools, which are softer than granite. Yet many Egyptian monuments are carved from granite with remarkable precision. Archaeologists have found that the builders used copper saws together with quartz sand: the hard sand grains, dragged by the saw blade, did the actual cutting. This suggests that ______

In a study of a small lake, ecologists found that the population of water fleas, tiny animals that eat algae, collapsed in the summer after a fish that eats water fleas was introduced. That same summer, the lake turned green with algae for the first time in years. The ecologists concluded that ______

A certain species of tropical tree produces fruit with an unusually thick, hard shell. No living animal in the tree's range can crack the shell, and fruits that fall to the ground usually rot without their seeds germinating. Fossil evidence shows that large ground-dwelling mammals with powerful jaws lived in the region until about ten thousand years ago. Botanists have suggested that ______

When a city lowered its speed limit from 50 to 30 kilometers per hour on residential streets, the number of crashes fell only slightly. However, the number of crashes causing serious injury fell by almost half. Because the force of a collision rises sharply with speed, this pattern suggests that ______

In the 1700s, European porcelain makers tried for decades to copy the fine porcelain imported from China. Many assumed that the secret lay in a special firing technique, and they built ever hotter kilns. But their pieces kept cracking. Success came only when a chemist in Saxony discovered that Chinese porcelain contained kaolin, a white clay not then used in Europe. This history suggests that the European makers' early failures resulted from ______

Researchers studying a population of wild chimpanzees noticed that some individuals used sticks to fish termites out of mounds, while others in the same group never did. The researchers recorded which young chimpanzees spent the most time near tool-using adults and found that these youngsters were far more likely to use sticks themselves as adults. Their observations suggest that ______

A company tested two versions of its website. In version A, the 'buy' button was green; in version B, it was red. Version B produced more sales. But the company had shown version B only during a holiday weekend, when shoppers typically spend more, and had shown version A on the ordinary weekdays before it. As a result, ______

The writer Mei Lin published her first three novels under a male pen name. Letters show that when she revealed her identity in 1902, several critics who had praised the novels began describing them as 'sentimental' and 'slight', though the books themselves had not changed. This episode suggests that ______

Hospital administrators noticed that patients treated by a particular surgeon had a higher death rate than patients treated by other surgeons at the same hospital. Before drawing conclusions, they learned that this surgeon was the hospital's specialist in emergency operations on very sick patients whom other surgeons had declined to treat. The administrators should therefore conclude that ______

For centuries, scholars believed that a medieval map of the world in a cathedral library had been drawn by a single artist. A recent analysis found that the ink used for the place names contains iron in a form that appears only in inks made after about 1350, while the ink used for the coastlines does not. Since the map's style dates the drawing of the coastlines to about 1290, the analysis suggests that ______

In a survey, people who owned dogs reported getting more exercise than people who did not. A newspaper concluded that getting a dog makes people more active. But a follow-up study tracked people before and after they adopted dogs and found that their exercise levels changed very little: those who adopted dogs had already been more active than average beforehand. This suggests that ______

Sociologist Teresa Oduya compared two neighboring towns with similar incomes. In Town A, most adults said they trusted their neighbors; in Town B, few did. Town A had several public spaces where residents met regularly, such as a weekly market and a shared sports field, while Town B had none. Oduya cautions, however, that trusting residents might also be more likely to create and use such spaces in the first place. Her caution implies that ______

Most of a tree's growth in width happens in a thin layer just under the bark. Foresters who wrap wire tightly around young trees to attach signs or fences sometimes find, years later, that the tree has died above the wire even though the wire never cut through the wood. Given where growth occurs, the most likely explanation is that ______

When the famous economist Hilde Brandt was asked why she preferred simple models to complex ones, she answered that a model with enough adjustable parts can be made to fit any past data perfectly. Such a model, she said, ______