Scientists are often asked to extrapolate conclusions based on given data. By observing the general trend of the data, we can infer the results of certain data points that were not explicitly tested. While graphs provide a visual representation of trends, we may have to use calculations to observe the trends of data given in tables.
The following ACT Science passage includes questions which will test your ability to observe trends. It is first important to establish a clear understanding of the information contained in the passage.
While it is important to understand the passage as a whole, trend questions can generally be answered by extrapolating from the given graphs and tables.
Question 1
This question is asking about the results found in Study 2. As we can see in the graph from Study 2 below, the x-axis which indicates temperature (℃) only goes up to 400. However, this question asks us what the thermal conductivity of rock salt at 500℃ would be. We can follow the trend of the graph and extrapolate to 500℃.
We can see that the rock salt graph is leveling off. By extending the graph, we can see that it is approaching a thermal conductivity of 2.
Therefore, the answer is B.
Question 2
This question asks us to observe trends based on the data provided in Study 3.
We can see that the graph from Study 3 indicates time in years on its horizontal axis. However, the graph only shows time up to 100,000 years, while the question is asking us to predict what the rock temperature increase (measured on the vertical axis) would be at 1,000,000 years in the future.
We can extrapolate the data through our visual understanding of the graph. We can see that the rock temperature increase peaked for all four types of rock at a little before 100 years, and then constantly decreased. At 100,000 years in the future, the rock temperature increase of all four rock types is almost 0. Based on the trend observed in the grpah, we can assume that the rock temperature increase will continue to decline over time. Therefore at 1,000,000 years, the rock temperature increase would be 0, since the answer choices suggesst that it cannot go below 0.
Therefore, the answer is E.