ACT Science

SAT Question of the Day

The SAT question of the day is a Number Line Question that has already been addressed on this blog: click here to see an explanation.

ACT Question of the Day

ACT science questions always follow a passage that often contains multiple figures.  Today's question, however, focuses on a single figure, so there is only one figure reproduced below.

The final stage of ecological succession is characterized by the presence of the climax community, the oak-hickory forest. Figure 3 depicts the gradual change from pine to hardwoods.


According to the information in Figure 3, a 150-year-old climax community would contain oak and hickory trees with a density of approximately:

Before you look at the answer choices, look up at Figure 3.  Look first at the horizontal axis.  Even though 150 years is not labeled, you can see that it would be a little less than halfway between 110 and 200.  If you imagine a vertical line going up from the year 150, where would that line cross the line labeled "oak-hickory"?  It meets this dotted line at approximately 15,000 trees per unit of area.  Look down at your answer choices.

F. 3,000 trees per unit area.

G. 5,000 trees per unit area.

H. 15,000 trees per unit area.

J. 20,000 trees per unit area.

(F) and (G) are far too low.  These numbers could only be chosen if you misread the labels on the lines in the chart.  (J) is much too high.  The oak and hickory trees do not reach 20,000 trees per unit area until just before 200 years, but you want the number at 150 years.

The correct answer is (H).

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