MathOne-Variable Data and StatisticsMedium frequency

SAT Math: Describe distribution shape: symmetric, skewed, bimodal

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What you need to know

The concept, explained

  • 1

    Symmetric distributions look mirrored around the center; mean ≈ median. Bell curves are a classic example.

  • 2

    Right-skewed (positively skewed) distributions have a long tail to the right. Mean > median because the tail pulls the average up.

  • 3

    Left-skewed (negatively skewed) distributions have a long tail to the left. Mean < median.

  • 4

    Bimodal distributions have two distinct peaks — often signaling two different subgroups mixed together.

Common mistakes
  • Confusing left-skew and right-skew. The direction refers to the tail, not the peak.
  • Assuming a symmetric distribution means mean = median exactly. In real data, they're only approximately equal.
Try a sample question

SAT-style practice

A histogram shows household incomes in a city: a tall bar at (30,000–)50,000, progressively shorter bars extending to $300,000+. Which best describes this distribution?

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