ACT Science Quiz: Interpreting Data From Graphs

What this quiz covers

This quiz focuses on Interpreting Data From Graphs, giving you a quick way to practice the rules, question types, and explanations that matter most for ACT Science.

How to use this quiz

Try each quiz question before looking at the correct answer. Use the explanations to review missed ideas, then come back to similar questions until the pattern feels familiar.

Question 1

1. May (correct answer)
2. June
3. July
4. April

Explanation: The bar graph compares rainfall totals for April (45 mm), May (62 mm), June (80 mm), and July (55 mm). May's bar at 62 mm is closest to 60 mm, as it's only 2 mm above while others differ more. This is correct because comparing bar heights to the target value identifies the nearest, demonstrating bar graph comparison. Option C, July at 55 mm, is close but farther from 60 than May.

Question 2

1. 18 million cells
2. 20 million cells
3. 24 million cells
4. 32 million cells (correct answer)

Explanation: The graph depicts bacterial population doubling every 2 hours, from 1 at 0 h, to 2 at 2 h, 4 at 4 h, 8 at 6 h, and 16 at 8 h. Extrapolating the trend to 10 h gives 32 million cells, as it doubles from 16. This is correct because continuing the pattern assumes the same growth rate, illustrating extrapolation from graphs. Option C, 24 million, might result from adding instead of multiplying.

Question 3

1. 55 °C
2. 85 °C (correct answer)
3. 65 °C
4. 120 °C

Explanation: The graph shows the temperature of the cooling rod decreasing over time, with the curve passing through points like (0, 200), (5, 120), (10, 85), (15, 65), and (20, 55). To find the temperature at 10 minutes, follow the x-axis to 10 min, go up to the curve, and read across to the y-axis, which gives approximately 85 °C. This is correct because the graph directly indicates 85 °C at that point, demonstrating how to read a specific value from a line graph. Option C, 65 °C, might be chosen if someone misreads the time as 15 minutes instead.

Question 4

1. Speed generally increases as ramp angle increases. (correct answer)
2. Speed remains constant across all ramp angles.
3. Speed generally decreases as ramp angle increases.
4. Speed increases up to 15° then decreases after 15°.

Explanation: The scatter plot shows cart speed increasing with ramp angle, with points clustering around (5, 0.6), (10, 1.0), (15, 1.4), (20, 1.9), (25, 2.3), and (30, 2.8). The overall trend is a steady rise, best described as speed generally increasing as ramp angle increases. This is correct because the pattern of points demonstrates a positive correlation, illustrating how to interpret trends in scatter plots. Option D might mislead if someone sees a false peak at 15° due to not viewing the full trend.

Question 5

1. Desert (correct answer)
2. Forest
3. Garden
4. Field

Explanation: The Desert habitat had the fewest insects observed according to Figure 1. Comparing the bar heights for all five habitats (Field, Forest, Pond, Garden, Desert), the Desert bar is clearly the shortest, indicating the lowest insect count during the 1-hour survey period.

Question 6

1. $5 \, \text{m/s}$
2. $15 \, \text{m/s}$ (correct answer)
3. $10 \, \text{m/s}$
4. $20 \, \text{m/s}$

Explanation: The speed at $1.5 \, \text{s}$ is closest to $15 \, \text{m/s}$. To find this value in Figure 1, locate $1.5 \, \text{s}$ on the x-axis, interpolate between the plotted points on the increasing trend line, then read across to the y-axis. The linear relationship shows speed increasing uniformly with time for the falling object.

Question 7

1. Wetland (correct answer)
2. Grassland
3. Urban
4. Forest

Explanation: Read the bar heights straight off the graph: Forest 18, Grassland 12, Wetland 25, and Urban 9 mean insects per trap. The wetland habitat has the tallest bar at 25, so it recorded the highest mean capture. Forest, at 18, is the runner-up and is the easiest trap to fall into if you grab the second-tallest bar or misread which bar you are on. Grassland at 12 and Urban at 9 are both clearly lower. With a bar graph comparison like this, find the value for every category before choosing, then pick the largest.

Question 8

1. increased only.
2. decreased only. (correct answer)
3. increased, then decreased.
4. remained constant.

Explanation: The correct answer is B (decreased only). All four oil curves in Figure 1 slope consistently downward from left to right — as temperature increases from 20°C to 80°C, drop time decreases for every oil tested. This is consistent with the passage's introduction, which states that viscosity decreases as temperature increases, and since lower viscosity means the ball falls faster, drop time decreases. A (increased only) and C (increased, then decreased) are contradicted by the uniformly downward-sloping curves. D (remained constant) would require flat horizontal lines, which is not shown. On trend questions, check all curves to confirm the trend is consistent — here all four oils show the same directional pattern.

Question 9

1. Troposphere and Mesosphere only (correct answer)
2. Stratosphere and Thermosphere only
3. Troposphere and Stratosphere only
4. Mesosphere and Thermosphere only

Explanation: The correct answer is A. Figure 1 shows temperature decreasing with altitude in two layers: the Troposphere (from 15°C at the surface down to −60°C at 12 km) and the Mesosphere (from 0°C at 50 km down to −90°C at 85 km). The Stratosphere shows increasing temperature with altitude (−60°C to 0°C), as does the Thermosphere (temperature increases rapidly above 85 km). B is wrong because both the Stratosphere and Thermosphere show temperature increasing with altitude. C is wrong because the Stratosphere shows temperature increasing, not decreasing. D is wrong because the Thermosphere shows temperature increasing. Pro tip: Read each layer's description carefully and classify it as either warming or cooling with altitude before looking at the answer choices.

Question 10

1. −80°C
2. −40°C (correct answer)
3. 0°C
4. 15°C

Explanation: The correct answer is B. An altitude of 30 km falls within the Stratosphere (12–50 km), where temperature increases from −60°C at 12 km to 0°C at 50 km. At 30 km, which is roughly the midpoint of this layer, the temperature is approximately −40°C. A (−80°C) is too cold — that value is closer to the Mesopause at 85 km. C (0°C) is the temperature at the Stratopause (50 km), not at 30 km. D (15°C) is the surface temperature at sea level. Pro tip: On atmospheric layer questions, first identify which layer the altitude falls in, then use the layer's temperature range to narrow your answer.

Question 11

1. the vaporization of an extraterrestrial asteroid.
2. the remnants of burned dinosaur bones.
3. magma plumes originating in Earth's deep mantle. (correct answer)
4. chemical reactions between carbon dioxide and shocked quartz.

Explanation: The correct answer is C. Scientist 2's hypothesis explicitly states: 'it is present in high concentrations in the deep mantle. The massive magma plumes from the Deccan Traps brought this deep-Earth iridium to the surface, where volcanic ash plumes spread it globally.' The iridium source in Scientist 2's model is the deep mantle, transported upward by magma. A describes Scientist 1's explanation for the iridium — asteroid vaporization. B is a fabrication not mentioned by either scientist. D combines two real elements from the passage (CO₂ and shocked quartz) in a relationship that neither scientist proposes. On viewpoint-specific detail questions, confirm which scientist's passage you are reading before selecting an answer.

Question 12

1. White Dwarf — because its high temperature of 10,000 K places it in the lower-left quadrant.
2. Main Sequence star — because its temperature and luminosity place it within the diagonal band. (correct answer)
3. Giant — because any star more luminous than the Sun must be a Giant or larger.
4. Supergiant — because a luminosity 100 times greater than the Sun indicates an extremely massive star.

Explanation: The correct answer is B (Main Sequence star). A luminosity 100 times greater than the Sun translates to 10² L☉ on the logarithmic y-axis. Locating 10,000 K on the x-axis and 10² on the y-axis and finding their intersection places this star within the Main Sequence diagonal band — it is a moderately hot, moderately luminous star that falls squarely on the sequence. A is wrong — White Dwarfs are in the lower-left (hot and dim); 10² luminosity is far too bright for a White Dwarf. C is tempting because Giants are more luminous than the Sun, but the specific coordinates of 10,000 K and 10² place this star on the Main Sequence band, not in the Giants region. D is wrong — Supergiants have luminosities of 10⁵ or greater; 10² is far too modest. The key skill here is correctly converting '100 times greater' to 10² on the logarithmic scale before locating the star.

Question 13

1. 85 km
2. 30 km (correct answer)
3. 50 km
4. 12 km

Explanation: This is a logarithmic scale reading question combined with interpolation. The phrase "requires at least [value] to function properly" combined with "maximum altitude" signals you need to find where a threshold is crossed on a graph. To solve this, locate 10 mb on the x-axis of Figure 2. Note that this is a logarithmic scale, so the spacing between 1, 10, and 100 is not linear—10 mb is closer to 1 mb than you might think on a regular scale. Trace upward from 10 mb to the exponential pressure curve, then trace left to read the altitude: approximately 30 km. At 12 km (Choice D), pressure is still around 200 mb (well above 10 mb threshold). At 50 km (Choice C), pressure has dropped to ~1 mb (below the threshold). Choice A (85 km) has even lower pressure (~0.01 mb). Pro tip: Logarithmic scales can be tricky—each tick mark represents a power of 10. Practice finding values between the major gridlines by estimating the exponential spacing!

Question 14

1. 24 h
2. 10 h (correct answer)
3. 18 h
4. 6 h

Explanation: The line graph shows dissolved oxygen concentration varying over 24 hours, decreasing to a low of about 6.5 mg/L at 10 h before rising again. The minimum value occurs at 10 h, as that's the lowest point on the curve. This is correct because tracing the curve to its lowest y-value and reading the x-axis gives 10 h, showing how to find minima on graphs. Option C, 18 h, could be mistaken if focusing on a high point instead.

Question 15

1. 110 g
2. 125 g (correct answer)
3. 140 g
4. 160 g

Explanation: The towel's mass at 15 min is closest to 125 g. To find this value in Figure 1, locate 15 min on the x-axis and trace up to the curve, then read across to the y-axis. The exponential decay curve shows rapid mass loss initially, and at 15 minutes the mass has decreased to approximately 125 g from its starting value.

Question 16

1. 0–1 m (correct answer)
2. 1–2 m
3. 2–3 m
4. 3–4 m

Explanation: The cart's speed increases the most over the 0–1 m distance interval. Examining Figure 1, compare the change in speed (vertical change) for each 1-meter interval. The steepest portion of the curve occurs in the first meter, where the cart accelerates most rapidly from rest, showing the largest increase in m/s per meter traveled.

Question 17

1. Plastic
2. Wood
3. Glass (correct answer)
4. Aluminum

Explanation: Glass has the greatest density according to Figure 1. Comparing the bar heights for all four materials (Aluminum, Glass, Wood, Plastic), the Glass bar extends highest on the y-axis, indicating it has the highest density value in g/cm³ among the tested materials.

Question 18

1. 35 °C
2. 45 °C (correct answer)
3. 55 °C
4. 70 °C

Explanation: The coffee temperature at 12 min is closest to 45°C. To find this value in Figure 1, locate 12 min on the x-axis, trace up to the exponential cooling curve, then read across to the y-axis. The curve shows rapid initial cooling followed by slower temperature decline, typical of cooling objects approaching room temperature.

Question 19

1. 85 °C
2. 90 °C
3. 95 °C (correct answer)
4. 100 °C

Explanation: The boiling point at 1,500 m altitude is closest to 95°C. To find this value in Figure 1, locate 1,500 m on the x-axis, then interpolate between the plotted points to estimate the corresponding boiling point on the y-axis. The downward trend shows that boiling point decreases with increasing altitude.

Question 20

1. 2 min
2. 6 min (correct answer)
3. 10 min
4. 14 min

Explanation: The subject's heart rate is highest at 6 min according to Figure 1. Examining the line graph across the entire time period, the peak of the curve occurs at 6 minutes, representing the maximum heart rate during the exercise and recovery protocol.