Study on the flyACTScienceInterpolation and extrapolation
Practice 76 Interpolation and extrapolation questions in the app
Interpolation and extrapolation on the ACT Science test covers estimating values that are not listed as exact data points.
Students must interpolate by reading a value between known points on a table, graph, or figure, and extrapolate by extending a trend beyond the given range. They have to pick the right variables, honor axis scales, and judge whether the target sits inside or outside the displayed data.
Questions usually attach a figure and offer nearby numerical estimates or competing trend claims as choices. Traps include the wrong series or axis, treating a curve as a straight line, and assuming a pattern keeps the same slope past the last plotted point.
Pick an answer to see whether it is right — nothing is saved, and nothing needs an account.
In a shallow pond, snails sometimes climb plant stems until they are above the water. During an approaching storm, researchers measured air pressure, dissolved oxygen in the water, and the percentage of visible snails above water. At air pressures of 102, 100, 98, and 96 kPa, dissolved oxygen concentrations were 8, 7, 5, and 4 mg/L, respectively. The corresponding percentages of snails above water were 12%, 26%, 61%, and 78%.
Three students explained the pattern.
Student 1
Snails directly detect falling air pressure and climb in response. Dissolved oxygen happens to fall before storms but is not the cue. At low pressure, snails will climb even if dissolved oxygen remains high.
Student 2
Snails climb when dissolved oxygen is low because they can obtain oxygen from air. Air pressure does not directly affect them. At low dissolved oxygen, snails will climb even if air pressure remains high.
Student 3
Neither low pressure nor low dissolved oxygen is sufficient alone. Both changes must occur together before most snails climb.
Researchers tested the explanations using 4 identical chambers. Each chamber contained 20 snails in pond water at the same temperature. In Chamber A, pressure was 102 kPa and dissolved oxygen was 8 mg/L. In Chamber B, the values were 96 kPa and 8 mg/L. In Chamber C, they were 102 kPa and 4 mg/L. In Chamber D, they were 96 kPa and 4 mg/L. After 30 min, the percentages of snails above water in Chambers A through D were 14%, 69%, 72%, and 76%, respectively. Each chamber was tested 5 times with new groups of snails, and the reported percentages are means. Light level, water depth, and the number of plant stems were kept constant.
Question 1Easier
Based on the pond observations, at an air pressure of 99 kPa, the percentage of snails above water would most likely have been between:
Answer: B — 26% and 61%.
A pressure of 99 kPa lies between 100 and 98 kPa, whose observed percentages were 26% and 61%.
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Practice 76 Interpolation and extrapolation questions in the app
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