CEnT-S reasoning on texts and data
The second section is fifteen questions in thirty minutes, the joint largest in the test. Its name misleads people: this is not a reading comprehension paper, and there are no long literary passages to work through. Most questions carry a chart or a table, and the skill being tested is reading a figure accurately under time pressure as much as reasoning about it.
The three strands
Logic
Conditional statements and what does and does not follow from them. If everyone who passes is offered a place, then a student with a place has not necessarily passed, because the statement leaves other routes open. Reversing a conditional this way is the single most common error in the section.
Necessary and sufficient conditions, the negation of quantifiers, and counterexamples. To make "all the samples contain lead" false, one clean sample is enough; the opposite universal, that none of them contain lead, is a far stronger claim and is not what the negation says.
A counterexample has to satisfy the condition and fail the conclusion. A figure that never met the condition cannot test the claim at all.
Data interpretation
Bar charts, grouped bars, line graphs, pie charts, histograms, scatter plots and tables. The questions ask for a mean, a median, a relative change, a count against a threshold, a proportion of a total, or the point where two lines cross.
Two distinctions carry most of the marks. Absolute against relative: a region that rises by eighteen points may have grown less, proportionally, than one that rose by fifteen from a smaller base. And mean against median: they coincide only when the data are symmetric, and the questions are not.
Problem solving
Ratio and proportion, percentages, and turning a written statement into an equation. Two tariffs with different fixed fees and different rates meet where their totals are equal, and both fixed fees have to stay in the equation.
Reading figures under time pressure
Two minutes a question, with most questions carrying a figure, leaves little room to study a chart carefully. A few habits pay for themselves.
- —Read the axis labels and the units before the data. A chart in thousands of tonnes and a question in tonnes differ by a factor of a thousand.
- —Check whether the question says "at least" or "more than". A value sitting exactly on the threshold is included by one and excluded by the other, and both counts will be among the options.
- —Where two lines nearly meet, they have probably not crossed yet. Sample charts are drawn so that the near miss and the crossing are one interval apart.
Where marks are lost
Answering from the chart's shape rather than its numbers. The tallest bar, the middle interval of a histogram and the midpoint of an axis all look significant and none of them answers a question about a mean or a median.
Counting outcomes rather than ways. Four totals of nine or more on two dice is not four outcomes out of thirty-six, because a total of nine arises four different ways and a total of twelve only one.
Confusing the coordinates. Where two lines cross, the x-value and the y-value are both on the page, and only one of them was asked for.
Practise the section
Fifteen original reasoning questions
Ten of them with charts or tables, under the real thirty-minute limit.
Start practice →