ACT Reading questions that ask about dates or time periods often appear deceptively easy. It’s easy to assume that all you have to do is go back to the passage and pick out the appropriate date. Even in a reading that includes a number of dates or years, that’s pretty straightforward once you find the correct spot in the passage, right?

Wrong.

These kinds of questions are actually inference questions in disguise, and answering them often requires you to take information from various parts of the passage and perform some very basic calculations.

For instance, one ACT passage asks about the time period when a particular kind of glass structure was least likely to be built in the United States.

Nowhere in the passage does the author actually come out and state the answer; (s)he only tells us that in the post-World War II period, many glass structures were built in the US, but that since 1973, most glass structures have been built in Europe.

We can therefore infer that after 1973, most glass structure were LESS likely to be built in the US than they were before. The answer, however, is 1975-1985 — only an approximation of what’s stated in the passage. A lot of people get confused because they can’t find a spot in the passage that states the year directly, and often they end up trying to justify a response that’s way off base.

I don’t want to suggest that the correct answer will never be directly stated in the passage; sometimes it will. But before you pick an answer just because you remember seeing it in the passage, make sure that it really does fit.