⚡ Quick Memory — Key Terms
📌 Instant Recall Points
Z = (X − μ) / σ
Z-score formula — always subtract mean, then divide by SD
68 – 95 – 99.7
Empirical Rule: 1σ / 2σ / 3σ covers these % of data
μ = 0, σ = 1
Standard Normal: always mean 0, SD 1
HIGHER Z = BETTER
Positive Z → above mean; higher Z = more standard deviations above
normalcdf
Area (probability) between two Z-scores on calculator
invNorm
Give % → get Z-score (reverse direction)
UNIMODAL + SYMMETRIC
Two defining properties of the normal curve
PERCENTILE = AREA LEFT
The percentile is always the area to the LEFT of the value
🟢 Part 1 — Foundation (Questions 1–5)
Quiz Complete 🎓
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