How to answer it
- Check that the sample was random and from the right population.
- Build the range: estimate minus and plus the margin of error.
- Choose the conclusion that stays inside that range and that population.
Worked example
An original question in the SAT format, already answered.
SAT MathWorked example
A random sample of 400 voters in a city found that 52% support a ballot measure, with a margin of error of 4 percentage points.
Which conclusion is most appropriate?
- AExactly 52% of the city’s voters support the measure.
- BThe measure will pass.
- CThe true share of supporters is plausibly between 48% and 56%.
- D4% of the city’s voters are undecided.
Answer: C. 52 ± 4 gives 48% to 56%. Because that range includes values below 50%, the sample can’t say the measure will pass.
The most common trap
Treating the estimate as exact. A margin of error means the true value could be anywhere in the range.
Practice it
Hourly Prep’s daily sets mix inference from sample statistics and margin of error with the rest of SAT Math, and send more of it your way when it’s a weak spot. See how the SAT prep plan works, or browse the other SAT skill guides.