Reading Data You Have Never Seen

The subject matter of these questions is deliberately unfamiliar, and it does not matter. Look at this table of minerals: you need no geology whatsoever to say which is hardest. It is topaz, because eight is the largest number in the hardness column, and that is the entire task. The names are just labels — you could replace them with A, B, C and D and nothing about the question would change. Unfamiliar vocabulary is there to unsettle you, and it carries no information you need.

Before answering anything, read the column headings and — more importantly — the units, because a table will often mix them on purpose. Here mass is in grams for two samples and kilograms for the third, and time is in minutes for two and seconds for the third. Comparing the bare numbers would make B look like the lightest, since one point two is the smallest figure in the column. Convert first: one point two kilograms is twelve hundred grams, which is heavier than nine hundred and fifty and four hundred. Mixed units are the trick, and converting everything to one unit defuses it.

Most of a table is decoration for any one question. Take how long is a day on the planet with the most moons. That is two steps: find the largest number in the moons column, which is fourteen for Halim, then read across that row to the day length, which is thirty-one hours. Notice the answer sits in a different column from the one you searched on — that is what makes these questions more than lookups, and reading across the wrong row is the commonest error. Put a finger on the row and keep it there.

To check whether two columns move together, sort by one of them and see whether the other follows. Sorting these planets by moons gives nought, two, seven and fourteen, and their day lengths in that order are nine, eighteen, twenty-five and thirty-one — also increasing. So in this table more moons goes with a longer day. But be careful about how strongly you state that. It is a trend in four rows, not a law of nature, and an option claiming that more moons always means a longer day, or that moons cause longer days, is going beyond what the page shows.

The hardest version gives you a rule in words and asks you to apply it to the data. A sample floats if its density is less than one point nought. Then you just test each row against that sentence: nought point eight is below one, so P floats; one point four is above, so Q sinks; nought point nine five is below, so R floats; two point one sinks. Two of them float. The discipline here is to use the rule exactly as written and not whatever you half-remember about floating, because the passage may well define things differently from real life, and it is the passage that is being tested. Quiz and exercises now.