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Interpreting Data from Graphs - ACT Science

  1. A student tested how the time to dissolve a tablet depends on water temperature. Figure 1 shows dissolve time versus temperature. Based on Figure 1, as water temperature increases, dissolve time:
    Answer: decreases from about 120 s to about 30 s. As water temperature increases, dissolve time decreases from about 120 s to about 30 s. Figure 1 shows a clear downward trend in the plotted points, demonstrating that higher temperatures cause tablets to dissolve more quickly. The relationship is inverse, with dissolve time dropping significantly as temperature rises from low to high values.
  2. A student recorded the temperature of cooling coffee after it was poured into a mug. Figure 1 shows temperature versus time. According to Figure 1, the coffee temperature at 12 min is closest to:
    Answer: 45 °C 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.
  3. A student recorded the number of customers entering a store each hour. Figure 1 shows customers per hour. According to Figure 1, during which hour was the store busiest?
    Answer: 14:00 The store was busiest during the 14:00 hour according to Figure 1. Examining the line graph of customers per hour, the peak occurs at 14:00 (2:00 PM), where the line reaches its highest point, indicating maximum customer traffic during the monitored period.
  4. A student compared the average time required for 4 different computers to complete a task. Figure 1 shows completion time. According to Figure 1, which computer completed the task fastest?
    Answer: C3 Computer C3 completed the task fastest according to Figure 1. Comparing the bar heights for all four computers (C1–C4), the C3 bar is the shortest, indicating the lowest completion time in seconds. The shortest time represents the fastest performance.
  5. Researchers heated a metal sample and recorded its temperature over time. Figure 1 shows temperature versus time for the sample during heating. Based on Figure 1, from 2 to 8 min the sample's temperature:
    Answer: increases overall, but the rate of increase slows after 6 min. The temperature increases overall from 2 to 8 min, but the rate of increase slows after 6 min. Looking at the slope of the line in Figure 1, the temperature rises steeply from 2 to 6 min, then continues to increase but with a gentler slope from 6 to 8 min. This shows that heating continues throughout but becomes less rapid in the later portion of the interval.
  6. Biologists observed bacterial population growth in a nutrient broth over several hours. Figure 1 shows population size versus time. If the trend from 4 to 8 hours continues to 10 hours, what population size would be the best estimate at 10 hours? Points are (0, 1), (2, 2), (4, 4), (6, 8), and (8, 16), connected by straight segments. Caption: The population approximately doubles every 2 hours over the interval shown; extrapolation beyond 8 hours assumes the same doubling pattern continues.
    Answer: 32 million cells 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.
  7. A student measured the density of different materials. Figure 1 shows the measured densities. According to Figure 1, which material has the greatest density?
    Answer: Glass 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.
  8. A student compared the average number of birds observed at 4 different locations. Figure 1 shows the averages. According to Figure 1, which location has the greatest mean birds observed per visit?
    Answer: Park The Park location has the greatest mean birds observed per visit according to Figure 1. Comparing the bar heights for all four locations (Lake, Park, Farm, City), the Park bar extends highest on the y-axis, indicating the highest average bird count during the observation visits.
  9. A student measured how the boiling point of water changes with altitude. Figure 1 shows boiling point versus altitude. Based on Figure 1, the boiling point at 1,500 m altitude is closest to:
    Answer: 95 °C 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.
  10. A chemist recorded the pH of a solution as increasing amounts of base were added. Figure 1 shows pH versus volume of base added. According to the graph, what is the pH when 30 mL of base has been added?
    Answer: 6.8 The graph illustrates pH increasing with volume of base added, passing through points like (0, 2.0), (10, 3.0), (20, 4.2), (30, 6.8), (40, 10.5), and (50, 12.0). At 30 mL, the pH is 6.8, found by going to 30 on the x-axis, up to the line, and across to the y-axis. This is correct because the graph directly provides the value at that point, teaching precise reading from plotted points. Option A, 4.2, might be chosen if misreading the volume as 20 mL.
  11. A student investigated how the period of a pendulum depends on pendulum length. Figure 1 shows period versus length. According to Figure 1, the period at a length of 0.80 m is closest to:
    Answer: 1.6 s The period at a length of 0.80 m is closest to 1.6 s. To find this value in Figure 1, locate 0.80 m on the x-axis, trace up to the data point, then read across to the y-axis. The plotted points show that pendulum period increases with length, and at 0.80 m the period is approximately 1.6 seconds.
  12. A student compared the average time it took 4 runners to complete a 5 km race. Figure 1 shows the times. According to Figure 1, which runner was fastest?
    Answer: R2 Runner R2 was fastest according to Figure 1. Comparing the bar heights for all four runners (R1–R4), the R2 bar is the shortest, indicating the lowest completion time in minutes. In racing, the shortest time represents the fastest performance.
  13. A student recorded the number of bacteria in a culture over time. Figure 1 shows bacterial count versus time. Between which two times does the bacterial count increase by the greatest amount?
    Answer: 6–8 h The bacterial count increases by the greatest amount between 6–8 h according to Figure 1. Examining the curve's steepness across different time intervals, the most rapid rise occurs in the final interval from 6 to 8 hours, where the exponential growth phase produces the largest increase in millions of cells.
  14. A student measured the number of bubbles produced by yeast at different sugar concentrations. Figure 1 shows bubbles per minute versus sugar concentration. According to Figure 1, bubble production is highest at approximately:
    Answer: 6% Bubble production is highest at approximately 6% sugar concentration according to Figure 1. The curve shows bubble production rate increasing with sugar concentration up to a maximum, then declining at higher concentrations. Following the curve to its peak and reading down to the x-axis shows optimal yeast activity occurs at about 6% sugar.
  15. A student compared the average number of steps taken per day across 5 people. Figure 1 shows the averages. According to Figure 1, who averaged the most steps per day?
    Answer: P4 Person P4 averaged the most steps per day according to Figure 1. Comparing the bar heights for all five people (P1–P5), the P4 bar extends highest on the y-axis, indicating the greatest average daily step count during the one-week measurement period.
  16. A student tracked the mass of a wet towel as it dried at room temperature. Figure 1 shows towel mass versus time. According to Figure 1, the towel's mass at 15 min is closest to:
    Answer: 125 g 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.
  17. A student measured the concentration of carbon dioxide (CO2_2) in a classroom over a class period. Figure 1 shows CO2_2 concentration versus time. According to Figure 1, the CO2_2 concentration at 40 minutes is closest to:
    Answer: 1,000 ppm The CO₂ concentration at 40 minutes is closest to 1,000 ppm. To read this from Figure 1, locate 40 min on the x-axis, trace up to the rising line showing CO₂ accumulation during class, then read across to the y-axis. The line shows steady increase in CO₂ concentration as students remain in the classroom.
  18. A student measured the speed of a falling object at different times after release. Figure 1 shows speed versus time. According to Figure 1, the speed at 1.5 s1.5 \, \text{s} is closest to:
    Answer: 15 m/s15 \, \text{m/s} The speed at 1.5 s1.5 \, \text{s} is closest to 15 m/s15 \, \text{m/s}. To find this value in Figure 1, locate 1.5 s1.5 \, \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.
  19. A student studied how the number of cars passing an intersection changes during the morning. Figure 1 shows cars counted per 10 minutes versus time. According to Figure 1, peak traffic occurs closest to:
    Answer: 8:30 Peak traffic occurs closest to 8:30 according to Figure 1. Examining the line graph of cars counted per 10-minute interval, the highest point on the curve represents maximum traffic volume. This peak occurs at approximately 8:30 during the morning traffic monitoring period.
  20. An ecologist compared the average number of insects captured per trap in four habitats during the same week. Figure 1 shows the mean insects per trap for each habitat. Which habitat had the highest mean capture?
    Answer: Wetland 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.

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