Problem-Solving and Data Analysis
15% of the SAT math section
Ratios, percentages and statistics: about seven questions, most of them word problems, all of them arithmetic that has to be set up from the right starting point.
Ratios, Proportions & Percentages
Navigating percent changes, unit conversions and proportional relationships. The single most common mistake is measuring a percent against the wrong amount — a discount is a percent of the original price, not of the price you ended up paying.
- A 20% discount means the customer pays 80% of the original price
Two-variable Data & Lines of Best Fit
A scatterplot with a line drawn through it, and three kinds of question: what the line’s slope means, what the line predicts at some , and how far one actual point is from that prediction. The line is a linear model like any other. The only new idea is that the points are not on it.
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- The model’s prediction at
Mean, Median & Spread
Interpreting centre (mean and median) and spread (range and standard deviation). The mean questions are the ones that look hardest and are not: a mean is a sum divided by a count, and the sum is the thing to find.
- Mean times count gives the sum of the original five
Probability & Two-way Tables
Probability on the SAT is a fraction read from a table: what you want over what you are choosing from. The trap is the denominator. “Selected at random from those who…” shrinks the pool to one row or one column, and the whole is no longer the whole table.
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- “A student who takes a bus”: the pool is the 120 bus riders