SAT Math: Estimating Standard Deviation from Graphs
17+ practice questions in Praczo
The concept, explained
- 1
Standard deviation measures how spread out the data is around the mean.
- 2
The SAT will NEVER ask you to calculate standard deviation by hand.
- 3
Instead, they will show two dot plots or histograms and ask which has a larger standard deviation.
- 4
A graph clustered tightly in the middle with few points on the edges has a SMALLER standard deviation.
- 5
A graph that is spread out uniformly or clustered at the extremes (bimodal) has a LARGER standard deviation.
- ✗ Thinking a taller peak means a larger variance/standard deviation (it actually means smaller, because more data is clustered together).
- ✗ Confusing standard deviation with the mean or range.
SAT-style practice
Dataset A contains values localized between 20 and 30. Dataset B contains values spread evenly between 10 and 40. Which has a larger standard deviation?
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