Module 10
見出し・軸・単位 （Midashi, Jiku, Tan'i）
帰国子女・インターナショナルスクール生のための、デジタルSAT 数学の無料教材。独学で進められます。
On a data question, the numbers in the table are rarely the whole story. The constraint that changes your answer is usually written in small text above or beside it: in thousands, per capita, in millions of dollars, ages 18–24 only.
Read the caption and both axis labels before you look at a single number. Five seconds spent there protects every calculation that follows.
日本語の表は、単位を見出しの中に短くはっきり書きます。「単位：千円」のように枠で囲まれていることが多く、見落としようがありません。英語はそれを見出しの中にまとめず、小文字のイタリック体の一句 "in thousands of dollars" として外に置きます。指示ではなく caption（説明書き）に見えます。時間に追われて数字だけを目で追っている受験生は、これが目に入りません。そのあとの答えは、すべて 1,000 倍ずれます。
The table below shows a company's annual revenue, in thousands of dollars.
Correct Answer: C
Explanation: 52 − 45 = 7, and the units are thousands of dollars, so the difference is 7 × 1,000 = $7,000.
Rated Medium. The arithmetic is a single subtraction a child could do; the entire difficulty is four words of italic English above the table.
A graph shows distance travelled, in kilometres, on the vertical axis and time, in hours, on the horizontal axis. The line passes through the points (2, 90) and (4, 180). What does the slope of the line represent?
Correct Answer: B
Explanation: Slope is vertical over horizontal, so its units are kilometres ÷ hours — kilometres per hour, which is speed. Numerically (180 − 90)/(4 − 2) = 45 km/h.
Rated Medium. You can answer it from the axis labels alone, without computing anything: the units of the slope are the units of the answer.
A table lists the mass of several samples in grams. One sample is listed as 2,500. What is the mass of this sample in kilograms?
Correct Answer: B
Explanation: 1,000 grams = 1 kilogram, so 2,500 ÷ 1,000 = 2.5 kg.
Rated Easy. The direction check — bigger unit, smaller number — eliminates D instantly and is worth applying to every conversion.