SAT Math: Margin of Error
15+ practice questions in Praczo
The concept, explained
- 1
Margin of Error gives a range of plausible values for a population parameter based on a sample relative value.
- 2
If a poll says 40% favor a policy with a 3% margin of error, the true population proportion is likely between 37% and 43%.
- 3
Margin of error decreases as sample size increases (a larger sample equals a more precise estimate).
- 4
It also depends on the variability of the data: more variability means a larger margin of error.
- 5
The SAT typically asks you to interpret the range or explain how sample size affects it, not to calculate it from scratch.
- ✗ Believing the true value MUST definitively be exactly the sample mean or within the range (it is just highly likely, not guaranteed).
- ✗ Assuming that a smaller sample size gives a smaller margin of error.
SAT-style practice
A random sample of birds yields an average wingspan of 12 cm with a margin of error of 1.5 cm. Which conclusion is best?
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