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SAT Reading & Writing: Hard Command of Evidence (Drill 7)

Drill 7 · Reading & Writing · Hard Command of Evidence

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About This Drill

SAT Reading & Writing: Hard Command of Evidence (Drill 7) is a Reading & Writing practice drill covering Hard Command of Evidence. It contains 5 original questions created by Brian Stewart, a Barron's test prep author with over 20 years of tutoring experience.

Five hard Command of Evidence questions built on new findings and two data displays. In each, three choices are true or nearly true but miss the precise relationship the argument requires. The graph and table items reward checking which contrast or which cell the claim actually depends on.

Questions & Explanations

Graph and Text
Sleep-Onset Delay by Evening Light and Age Group 0 15 30 45 60 Onset delay (min) Age group Teens Adults Older adults Dim light Bright light

A sleep lab tested whether bright light in the evening pushes back the time people fall asleep, and whether the effect depends on age. It measured how long sleep onset was delayed under dim versus bright evening light in three age groups. The lab concluded that bright evening light delays sleep mainly in teenagers, reasoning that a treatment that disrupts the body clock should set back sleep far more in the young than in older people if the young are the most sensitive.

Question 1. Which choice best describes data from the graph that support the lab's conclusion?

  • A) Under bright evening light, sleep onset was delayed more for teenagers than for either of the two older age groups that were measured.
  • B) Among teenagers, sleep onset was delayed longer under bright evening light than under dim evening light.
  • C) Bright light delayed sleep onset far more than dim light among teenagers but made only a small difference for adults and older adults. ✓
  • D) Under dim evening light, the shortest sleep-onset delay of any group belonged to the older adults.

Explanation: Choice C is the best answer because the conclusion is that bright light delays sleep mainly in teens, which is a claim about where the dim-to-bright gap is largest. The graph shows a large gap for teens, about 18 versus 52 minutes, but much smaller dim-to-bright differences for adults and older adults, so the disruption is concentrated in the youngest group. Choice A is wrong because a longer bright-light delay for teens than for older groups compares one series across ages and does not show the dim-to-bright gap is concentrated in teens. Choice B is wrong because a longer delay under bright than dim light for teens alone is true but does not show the effect is specific to teens rather than shared across ages. Choice D is wrong because where the dim-light delay is shortest concerns the wrong comparison and does not speak to the dim-versus-bright gap by age.

Text

A newly described fossil animal has long forelimbs and a lightweight, hollow-boned skeleton. Paleontologists proposed that it was capable of powered flight, flapping under its own muscle power rather than only gliding from tree to tree. They wanted to distinguish true flapping flight from mere gliding, which a light skeleton alone would not establish.

Question 2. Which finding, if true, would most directly support the paleontologists' proposal?

  • A) The fossil animal's hollow bones closely resemble, in the thinness of their walls and their internal structure, the bones of several other lightweight ancient animals known from the same rock formations.
  • B) The animal's breastbone bears a deep central ridge of the kind that anchors the large muscles used to power a flapping wingbeat. ✓
  • C) The animal's long forelimbs were roughly the same length as its hind limbs rather than noticeably shorter.
  • D) Fossils of the animal are most often found in rock layers that formed in what were once heavily forested regions.

Explanation: Choice B is the best answer because the proposal is specifically powered, flapping flight, which depends on large flight muscles, not just a light body. A deep breastbone ridge that anchors the muscles driving a wingbeat is direct evidence the animal could flap under its own power rather than only glide. Choice A is wrong because hollow bones like those of other light animals fits gliding as easily as flapping and does not single out powered flight. Choice C is wrong because the relative length of the limbs does not show whether the animal could flap under muscle power. Choice D is wrong because a forested habitat would suit a glider just as well, so it does not establish powered flight.

Text

After a city opened a new commuter rail line to a formerly quiet district, the number of businesses in that district rose sharply. Economists proposed that the rail line itself spurred the growth, by making it easy for customers and workers to reach the district. A rival account holds that the district was already growing for other reasons and would have added businesses even without the rail line.

Question 3. Which finding, if true, would most directly support the economists' proposal?

  • A) Several of the new businesses that opened in the district were restaurants and shops rather than offices or warehouses.
  • B) The district had a number of vacant storefronts available for rent in the years just before the new rail line opened.
  • C) A comparable district with similar earlier growth but no new rail line added far fewer businesses over the same period. ✓
  • D) The new commuter rail line runs trains into the district at frequent intervals throughout the day and into the evening.

Explanation: Choice C is the best answer because the economists credit the rail line rather than growth that was already underway, so the evidence must separate the two. A comparable district with similar prior growth but no rail line adding far fewer businesses isolates the rail line as the driver, since the shared earlier growth did not by itself produce the surge there. Choice A is wrong because the types of businesses that opened is a side detail that does not address what caused their numbers to rise. Choice B is wrong because available vacant storefronts is background about capacity and does not link the growth to the rail line. Choice D is wrong because describing the frequent train service restates a feature of the line without showing it produced the new businesses.

Table and Text

Average Daily Iron Intake (mg) by Diet Group and Flour Type

Diet groupStandard flourIron-fortified flour
Group X1114
Group Y716
Group Z1315

A study measured daily iron intake for three diet groups eating bread made from either standard flour or iron-fortified flour. A nutritionist wanted to know which group's intake rose the most when its bread was switched to the fortified flour. The data show that switching to the fortified flour raised iron intake by the widest margin for ________

Question 4. Which choice most effectively uses data from the table to complete the statement?

  • A) Group Z, whose fortified-flour intake of 15 milligrams was higher than Group X's.
  • B) Group Y, whose intake climbed from 7 milligrams on standard flour to 16 on the fortified flour. ✓
  • C) Group X, where the standard flour and the fortified flour produced fairly close intake levels.
  • D) Group Z, which already had the highest average iron intake of any group while it was still eating the standard, unfortified flour.

Explanation: Choice B is the best answer because the statement asks which group's intake rose most when its flour was switched. The increase is 3 milligrams for Group X, 11 to 14, and 2 for Group Z, 13 to 15, but 9 milligrams for Group Y, 7 to 16, so Group Y gains by the widest margin. Choice A is wrong because Group Z's fortified intake being higher than Group X's compares across groups, not the rise within Group Z, which the question asks about. Choice C is wrong because Group X shows only a small change between the two flours, a narrow margin, not the widest. Choice D is wrong because Group Z having the highest standard-flour intake concerns the starting level, not how much the switch raised intake.

Text

Engineers added a pressure sensor to a robot's gripper and found it could then pick up fragile objects, like eggs, without crushing them, which it had often failed to do before. They proposed that the sensor enables this by letting the gripper feel how hard it is squeezing and ease off in time. A skeptic suggested the gripper might now simply close more gently on everything, sensor or no sensor.

Question 5. Which finding, if true, would most directly support the engineers' proposal?

  • A) With the sensor switched off, the gripper crushed fragile objects just as often as it had before the sensor was installed. ✓
  • B) The new pressure sensor adds only a small amount of weight and cost to the robot's gripper assembly.
  • C) After the sensor was added, the gripper was able to handle a noticeably wider range of differently shaped and differently sized objects than it had managed to handle before.
  • D) The robot's gripper is built from a hard, rigid material rather than a soft or flexible one.

Explanation: Choice A is the best answer because the proposal is that the sensor's feedback is what lets the gripper ease off, so the evidence must show the gains depend on the sensor working. With the sensor switched off the gripper crushing fragile objects as often as before shows the improvement vanishes without active sensing, which points to the feedback rather than a generally gentler grip. Choice B is wrong because the sensor's weight and cost are practical details unrelated to why the gripper stopped crushing fragile objects. Choice C is wrong because handling more shapes shows added versatility but not that the sensor's feedback, rather than a softer grip, prevents crushing. Choice D is wrong because the gripper being made of rigid material is background and does not show the sensor's feedback is responsible.