Working with findings

Where the answer comes from: the passage states that in Year 1 "the fertilized plots produced 195 bushels per acre, compared with 150 bushels per acre," and in Year 2 "the fertilized plots produced 95 bushels per acre, compared with 92 bushels per acre."

Step by step:

1. Year 1 effect of fertilizer: 195 - 150 = 45 bushels per acre (that is 45 \div 150 = 0.30, a 30% increase).
2. Year 2 effect of fertilizer: 95 - 92 = 3 bushels per acre (only about a 3% increase).
3. So the fertilizer gave a large boost in the wet year and almost no boost in the drought year.

Correct answer: B. Choice A reverses the years. Choice C ignores the large Year 1 gain. Choice D is wrong because the fertilized plots still yielded slightly more (95 vs. 92) in Year 2.

Tip: Before you try to explain two findings, state each one precisely in numbers. Many "working with findings" questions start by asking you to see exactly what is different.

Where the answer comes from: the passage says Year 1 had "28 inches of rain" and Year 2 "was a drought, with only 9 inches of rain." Soil moisture "was 31% in Year 1 and 9% in Year 2." It also says "the same brand and amount of fertilizer was used both years."

Step by step:

1. The fertilizer, corn variety, number of plots and planting date stayed the same. The big difference between the years was water.
2. Plants need both water and nutrients. If water is in short supply, adding more nutrients cannot make the plants grow much more, because water is now the limiting factor.
3. This one idea explains both results: with plenty of water (Year 1), nutrients were what held the corn back, so fertilizer helped. With little water (Year 2), extra nutrients barely helped.

Correct answer: C. Choice A has no support: the passage says the fertilizer was the same. Choice B contradicts the data, since fertilized plots still did slightly better in the drought. Choice D throws away a finding instead of explaining it.

Tip: A good reconciling explanation keeps all the findings true and points to a real difference in conditions between the studies.

Where the answer comes from: the explanation being tested is that low water (soil moisture of 9% in Year 2) kept the fertilizer from working. To support it, you need evidence where water is added back and the fertilizer effect returns.

Step by step:

1. Choice B describes plots in a drought year that are irrigated (watered). If the fertilizer again raised yield by about 30%, as in Year 1 (45 \div 150 = 30\%), then water really was the missing piece.
2. Choice A only shows the corn was smaller in Year 2. That is true for both fertilized and unfertilized plots and does not say why the fertilizer failed.
3. Choice C is about other farms and other practices, so it does not test the explanation.
4. Choice D is about temperature, a different factor; it would point to a different explanation, not support this one.

Correct answer: B.

Tip: Evidence that best supports a cause-and-effect explanation usually comes from changing the suspected cause (here, water) while keeping everything else the same.

Where the answer comes from: the table rows "| 10° | 120 | 30 |", "| 20° | 260 | 45 |" and "| 30° | 510 | 70 |" give the soil lost (in grams) from the bare and grass-covered trays.

Step by step:

1. At every slope, the grass-covered tray lost less soil than the bare tray.
2. The gap grows with slope: 120 - 30 = 90 g, then 260 - 45 = 215 g, then 510 - 70 = 440 g.
3. Both columns rise with slope, but the bare column rises much faster.

Correct answer: C.

Check: the bare tray lost 4 times as much at 10° (120 \div 30) and about 7 times as much at 30° (510 \div 70 \approx 7.3), so the ratio is not a steady "about twice."

Tip: To describe a finding, state the direction (less soil lost with grass) and how the difference changes across conditions (bigger on steeper slopes).

Where the answer comes from: the table rows run from "| 28 | 2 |" and "| 29 | 5 |" up to "| 30 | 18 |", "| 31 | 47 |" and "| 32 | 81 |".

Step by step:

1. Increase per 1 °C step: 5 - 2 = 3, 18 - 5 = 13, 47 - 18 = 29, 81 - 47 = 34 percentage points.
2. Bleaching stays low (2% and 5%) at 28 °C and 29 °C.
3. Above 29 °C, each extra degree adds a much larger amount, so bleaching rises sharply.

Correct answer: B.

Check: the steps (3, 13, 29, 34) are not equal, so a "same amount each degree" statement is wrong; and at 30 °C only 18% bleached, so "most colonies" is wrong there.

Tip: To describe a table, compute the change between rows. Unequal changes tell you the pattern speeds up or slows down.

Where the answer comes from: the passage says every thermometer "read 0.0 °C" in ice water, the water was distilled, and the Miami class using "the same brand of thermometer and the same kind of distilled water" measured about 100 °C. The key difference: air pressure "was about 83 kilopascals (kPa) in Denver and about 101 kPa in Miami."

Step by step:

1. Rule out faulty thermometers: they were checked in ice water, and the same kind worked as expected in Miami.
2. Rule out impure water: the water was distilled in both cities. (Dissolved impurities actually raise the boiling point, so impurities would not explain a lower reading.)
3. Rule out a weak burner: water that is truly boiling stays at its boiling point no matter how hard you heat it.
4. What remains is the real difference: Denver's lower air pressure. With less air pressing down on the water's surface, water molecules escape as vapor more easily, so water boils at a lower temperature.

Correct answer: A.

Tip: When results are unexpected, first eliminate errors the passage has already ruled out, then look for a real difference in conditions.

Where the answer comes from: the graph shows the rate peaking at 12 units per minute at 40 °C, with 9 at 30 °C and 6 at 50 °C. The passage says that "above 40 °C the rate dropped quickly, to 1 unit per minute at 60 °C."

Step by step:

1. 25 °C lies between 20 °C (5) and 30 °C (9), so its rate is about 7 units per minute.
2. 38 °C lies just below the peak at 40 °C, between 9 and 12, so its rate is about 11 units per minute — the highest of the choices.
3. 55 °C lies between 50 °C (6) and 60 °C (1), so its rate is only about 3 to 4.
4. 70 °C is beyond the tested range. The trend after 40 °C is sharply downward and the enzyme denatures, so it would be slower still, not faster.

Correct answer: B (38 °C).

Tip: Applying findings to a real situation often means interpolating (estimating between tested values). Be very cautious about extrapolating beyond the data, and never assume a trend reverses.

Where the answer comes from: the table gives freezing points of −3.0 °C (5 g), −6.0 °C (10 g) and −12.0 °C (20 g). Using the pattern of about 3 °C per 5 g, 15 g gives about −9.0 °C.

Step by step:

1. To stay liquid at −8 °C, the solution's freezing point must be colder than −8 °C.
2. 5 g → −3.0 °C: freezes at −8 °C. Not enough.
3. 10 g → −6.0 °C: −6 is warmer than −8, so it still freezes. Not enough.
4. 15 g → about −9.0 °C: −9 is colder than −8, so it stays liquid. ✓
5. 20 g → −12.0 °C also works, but it is not the smallest amount.

Correct answer: C (15 g).

Tip: With negative temperatures, "colder" means "more negative." Compare carefully: −9 °C is colder than −8 °C, but −6 °C is warmer.

Where the answer comes from: the table shows soil loss for both covers at three slopes: "| 10° | 120 | 30 |", "| 20° | 260 | 45 |" and "| 30° | 510 | 70 |".

Step by step:

1. Plant grass, keep 25°: 25° lies between 20° and 30°, so a grass-covered tray would lose between 45 g and 70 g.
2. Reshape to 20°, bare: about 260 g, far more.
3. Reshape to 10°, bare: about 120 g. Even the gentlest bare tray lost more than the steepest grass-covered tray (70 g).
4. Gravel: gravel was never tested, so the findings cannot support it.

Correct answer: C.

Check: every grass-covered value (30, 45, 70 g) is lower than every bare value (120, 260, 510 g), so plant cover mattered more than slope in this test.

Tip: When you apply findings to a decision, estimate the outcome of each option from the data and stay inside what was actually tested.

Where the answer comes from: the counts rise from 8 stars at 2 km to 54 stars at 50 km, then "| 80 | 60 |" and "| 120 | 61 |" show only small gains.

Step by step:

1. From 2 km to 50 km the count climbs steeply: 8, 15, 31, 54.
2. From 50 km to 80 km it rises by only 6; from 80 km to 120 km, by only 1.
3. So the count rose with distance and then leveled off beyond about 80 km.
4. The data describe what observers saw. They do not show that the stars themselves changed brightness.

Correct answer: D.

Check: test the doubling claim: from 25 km to 50 km the count went from 31 to 54, not 62.

Tip: A supported conclusion describes the pattern the data actually show, including where it changes, and does not reach beyond the data range.

Where the answer comes from: in the lab, "Volunteers first washed and dried their hands." In the field, "Their hands were covered with visible grease and dirt." The field test used the "same harmless test bacteria" and "the sanitizer came from the same batch."

Step by step:

1. Same sanitizer batch, same amount (3 mL), same bacteria, same room temperature.
2. The one big difference is clean hands (99.9% killed) versus greasy, dirty hands (about 60% killed).
3. So the most reasonable explanation is that grease and dirt get in the way of the sanitizer reaching the bacteria.

Correct answer: D.

Check: the explanation keeps both results true. Saying the lab result is wrong, or that the bacteria or batch were different, contradicts the passage.

Tip: When two tests of the same product disagree, list the controlled factors first. Whatever is left over is your best explanation.

Where the answer comes from: the first sample showed "0.04 at 16 µg/mL" (no growth). The passage also states: "Some bacteria carry a gene that lets them break down or pump out an antibiotic. Bacteria with such a gene are called resistant."

Step by step:

1. Same species, same test, very different result: 0.82 versus 0.04 at 16 µg/mL.
2. The passage gives a ready explanation: some bacteria carry a resistance gene. The second patient's bacteria most likely have it.
3. The idea that the antibiotic helps bacteria grow is contradicted by the first test, where 16 µg/mL stopped growth.
4. Nothing in the passage says the temperature changed; the test used 37 °C, and "the same test" was run.

Correct answer: B.

Check: a good explanation of an unexpected result fits both the old and new findings. Resistance explains why one sample died and the other did not.

Tip: When a result surprises you, do not throw out the earlier data. Look for a difference between the two samples that the passage gives you.

Where the answer comes from: the log says "Day 7: a cold, heavy rain soaked the pile all night." The passage also says "The microbes work best when the pile is damp but not soaked." The thermometer "read correctly both times" when it was tested.

Step by step:

1. The drop appears on day 8, right after the night of cold rain.
2. Cold water cools the pile directly, and a soaked pile slows the microbes, so they release less heat. Both lower the temperature.
3. By day 10, after the pile was turned and aired out, it was back to 60 °C, so the microbes were still alive.
4. Turning the pile happened on day 9, after the day 8 reading, so it cannot explain it.

Correct answer: C.

Check: the explanation must come before the effect in time and push the temperature in the right direction (down). Only the rain does both.

Tip: For unexpected-result questions, line up the timeline. A cause must happen before the result it explains.

Where the answer comes from: in Study 1, people walked "5 days a week, for 8 weeks" and pressure "fell from 138 to 131 mmHg." In Study 2, people walked "once a week for 8 weeks" and pressure "went from 137 to 136 mmHg." Study 2 used "adults of the same ages."

Step by step:

1. Study 1 change: 131 - 138 = -7 mmHg, versus -1 in its no-exercise group, a real difference of about 6 mmHg.
2. Study 2 change: 136 - 137 = -1 mmHg, versus 0 in its no-exercise group, almost no difference.
3. Same ages, same kind of patients, same 30-minute walks, same 8 weeks, same measuring method. The main difference is how often people walked.

Correct answer: B.

Check: this explanation keeps both findings true. It does not throw out either study.

Tip: To reconcile two findings, find the condition that differed between the studies and show how it could produce both results.

Where the answer comes from: the two studies differ mainly in walking frequency: "5 days a week" in Study 1 and "once a week" in Study 2. The explanation says more days give more benefit.

Step by step:

1. If frequency matters, an in-between schedule should give an in-between result.
2. A third study at 3 days a week with a drop of about 4 mmHg falls neatly between Study 2 (about 1 mmHg) and Study 1 (about 7 mmHg). That is a dose-response pattern: more walking days, bigger drop.
3. Enjoying the walks says nothing about blood pressure.
4. A cold winter during Study 2 would offer a different explanation and so would weaken the frequency idea.
5. The no-exercise groups barely changing is already known from the passage; it does not test frequency.

Correct answer: D.

Check: ask whether the finding would make the explanation more likely. Only the 3-day result does.

Tip: Strong support for "more X gives more Y" is a middle amount of X that gives a middle amount of Y.

Where the answer comes from: the table gives "| 31 | 47 |" and "| 32 | 81 |".

Step by step:

1. 31.5 °C is between 31 °C and 32 °C.
2. The trend rises steadily in that range, so the bleaching should fall between 47% and 81%.
3. A rough middle estimate is \dfrac{47 + 81}{2} = 64\%, which is inside that range.

Correct answer: C.

Check: the range 18% to 47% belongs to 30–31 °C, which is cooler than the forecast. Above 81% would need a temperature above 32 °C.

Tip: To apply a finding to a new value, locate the two data rows that bracket it. The prediction should land between their results.

Where the answer comes from: the table lists "| Mercury | 0.39 | 167 | almost none |", "| Venus | 0.72 | 464 | very thick, mostly carbon dioxide |" and "| Mars | 1.52 | −65 | thin, mostly carbon dioxide |", along with Earth and Jupiter.

Step by step:

1. From Venus outward, temperature falls with distance: 464, 15, −65, −110 °C. So farther planets are generally colder.
2. But Venus (0.72 AU) is hotter than Mercury (0.39 AU), even though Mercury is closer. Distance alone cannot explain that.
3. Mars also has a carbon dioxide atmosphere but is very cold (−65 °C), so carbon dioxide does not make every planet hot.
4. The drops in temperature are not equal per AU (for example, 449 °C from Venus to Earth but only 45 °C from Mars to Jupiter over a much larger distance).

Correct answer: D.

Check: a supported conclusion must fit every row, including the exceptions.

Tip: Look for the data point that breaks the general trend. The best conclusion states the trend and admits the exception.

Where the answer comes from: Study 1 shows survival of 82% in clean water and 80% at 0.01 ppm, but only 61% at 0.05 ppm and 48% at 0.10 ppm. Study 2 says "the farm ponds contained an average of 0.008 ppm of pesticide X."

Step by step:

1. In the lab, harm clearly appears at 0.05 ppm and above. At 0.01 ppm, survival (80%) is nearly the same as in clean water (82%).
2. The farm ponds held only 0.008 ppm, which is even lower than 0.01 ppm — below the level that caused harm in the lab.
3. So we would expect farm ponds and preserve ponds to have similar frog numbers (140 vs. 145). Both studies can be correct at the same time.

Correct answer: D. Choice A dismisses the field data instead of explaining it. Choice B makes an unsupported claim about immunity. Choice C contradicts Study 1, which showed clear harm at 0.05 and 0.10 ppm.

Tip: Two studies that seem to disagree often tested different conditions (here, different concentrations). Look for that difference before deciding one study is wrong.

Where the answer comes from: the students' explanation rests on their observation that "the grass roots formed a thick mat in the top few centimeters of soil." They think the roots, not the leaves, are what hold the soil.

Step by step:

1. To weaken a "roots do the work" explanation, look for a case where the roots are still there but the soil still washes away.
2. Trays with the grass cut off at ground level still have all their roots. If they lose about as much soil as bare trays, the roots alone did not protect the soil, and the leaves (which break the force of falling water) may matter more.
3. Deeper roots giving less loss, or roots-only trays protecting the soil, would support the conclusion.
4. Sandy soil is a different variable; it says nothing about the role of roots.

Correct answer: D.

Check: ask "If this were true, would I believe the roots explanation less?" Only the cut-grass finding makes you doubt it.

Tip: Weakening evidence shows the proposed cause present without the effect (or the effect without the cause).

Where the answer comes from: the table shows "| 2 | 8 |": only 8 stars were counted at 2 km. The passage notes "The city's streetlights, signs and buildings send light up into the sky, which makes the night sky glow."

Step by step:

1. If city light is the cause, turning the lights off should let a nearby observer see many more stars.
2. A citywide power outage is a natural test. If the 2-km count stayed at about 8, removing the light did not help, so something else (such as haze or dust over the city) must be limiting the view. That weakens the conclusion.
3. A count of 52 during the outage would support the conclusion.
4. The same pattern near another city also supports it.
5. Haze lowering counts far from the city is a different factor; it does not show that city light is unimportant.

Correct answer: C.

Check: weakening evidence removes the suggested cause and finds that the effect does not change.

Tip: Look for a "switch-off" test: if taking away the cause leaves the effect in place, the cause is in doubt.

Where the answer comes from: the table shows the length rising 2.5 cm per 100 g up to "| 400 | 20.0 |", then "| 500 | 22.0 |" and "| 600 | 23.0 |". After the 600-g load, "the spring stayed at 11.2 cm."

Step by step:

1. Steps from 0 to 400 g: 10.0 → 12.5 → 15.0 → 17.5 → 20.0, each +2.5 cm.
2. From 400 to 500 g: +2.0 cm. From 500 to 600 g: +1.0 cm. The stretch per 100 g got smaller.
3. The spring did not return to 10.0 cm after 600 g, so it was permanently changed.
4. Doubling the mass from 100 g to 200 g changed the length from 12.5 to 15.0 cm, not to 25.0 cm.

Correct answer: B.

Check: a conclusion that uses the words "always" or "no matter how much" fails if even one row breaks the pattern, and the 500- and 600-g rows do.

Tip: Watch for where a pattern stops. A supported conclusion states the range in which it holds.

Where the answer comes from: the sanitizer "killed 99.9% of the test bacteria" on clean hands but "killed only about 60% of the test bacteria" on greasy, dirty hands.

Step by step:

1. To support "grease and dirt are the cause," test the same mechanics with the grease removed.
2. If washing the grease off brings the kill rate back to 99.8%, then the grease and dirt, not the people or the job, made the difference.
3. A different sanitizer strength on clean hands says nothing about grease.
4. Shift length and stinging cuts are not measurements of how many bacteria were killed.

Correct answer: A.

Check: the best supporting evidence works like a controlled experiment: change only the suspected cause and watch the result change.

Tip: When asked for the "best" support, prefer a finding that isolates the proposed cause over one that is merely related to the topic.

Where the answer comes from: Study 1 found 82% survival in clean water and 48% at 0.10 ppm. Study 2's farm ponds had only 0.008 ppm, far below 0.10 ppm.

Step by step:

1. The new pond's predicted level (0.10 ppm) matches a concentration tested in Study 1, so Study 1 is the relevant finding.
2. Survival would fall from about 82% to about 48%: 82 - 48 = 34 percentage points, or 34 \div 82 \approx 0.41, about 41% fewer tadpoles surviving.
3. Study 2 cannot be used to predict "no change," because its ponds had about one-twelfth of that concentration (0.10 \div 0.008 = 12.5).
4. With fewer young frogs surviving each spring, the adult population would likely shrink over time.

Correct answer: A. Choice B misapplies Study 2. Choice C overreaches: 48% survival is not zero, and nothing supports extinction "within one year." Choice D has no support at all.

Tip: When you apply findings to a new case, use the study whose conditions match the new case, and pick the prediction that stays closest to what the data actually show.

Where the answer comes from: the survey "recorded the highest water temperature reached at each site" and found, for example, "| 32 | 81 |": 81% of colonies bleached at 32 °C.

Step by step:

1. If temperature alone decided bleaching, colonies at the same temperature should bleach about equally.
2. Shaded colonies at 32 °C bleaching far less than unshaded colonies at the same 32 °C shows that something besides temperature (here, sunlight) also matters. That directly weakens "by itself."
3. 92% bleaching at 33 °C continues the temperature trend and supports the role of temperature.
4. Bleaching that starts a few days after the peak temperature fits temperature as a cause.
5. Aquarium corals bleaching at 32 °C also supports temperature as a cause.

Correct answer: A.

Check: none of the wrong choices shows a difference in bleaching when temperature is held the same.

Tip: Claims with "alone," "only" or "by itself" are weakened by any case where the factor stays the same but the result changes.