SAT Math Practice Question #2507 (Medium) | Test Citadel
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SAT Math Difficulty: Medium

Digital SAT Math Practice Question #2507

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A class of 24 students took a test; 12 scored 80 and 12 scored 100. What is the standard deviation?
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Socratic AI Engine Step-by-Step Derivation
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⚡ 15-Second Desmos Speed Hack

Desmos / Statistical Reason: Filter conditional probability denominators carefully — 'out of what total' is always the key.

Masterclass Solution & Distractor Trap Analysis

Mean is 90. Deviations are $-10$ and $+10$. Variance $= \frac{12(-10)^2 + 12(10)^2}{24} = 100$. Standard deviation $= \sqrt{100} = 10$....

Distractor Analysis: Trap choice eliminates careless test-takers who confuse roots with coordinates...

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