Normal Distribution & IQ Scores – AP Psychology | ShowMeClass

IQ

Normal Distribution & IQ

AP Psychology · Unit 7: Testing & Individual Differences

Learning Objectives

Understand the normal (bell) curve

Apply the 68-95-99.7 rule

Interpret IQ scores and percentiles

Convert between z-scores and raw scores

IQ Score Ranges

130+: Very Superior (~2.2%)
120-129: Superior (~6.7%)
110-119: High Average (~16.1%)
90-109: Average (~50%)
80-89: Low Average (~16.1%)
70-79: Borderline (~6.7%)
<70: Intellectual Disability (~2.2%)

68-95-99.7 Rule

68% within ±1 SD (85-115)
95% within ±2 SD (70-130)
99.7% within ±3 SD (55-145)

Colors

Normal distribution

Selected score

SD bands

IQNormal Curvez-score

IQ Score:100

z-score:0.00

Percentile:50th

Classification:Average

IQ Score

100

Raw score

z-Score

0.00

Standard deviations

Percentile

50.0

% below this score

Rarity

1 in 2

People at or above

Category

Average

Classification

IQ Score 100

Mean (μ) 100

Std Dev (σ) 15

Display

Test Scale

Score Analysis

Quick Quiz▼

1. On a standard IQ test, the mean and SD are:

Mean=50, SD=10 Mean=100, SD=15 Mean=100, SD=10 Mean=500, SD=100

2. About 68% of people have IQ scores between:

70-130 85-115 90-110 55-145

3. An IQ of 130 is at approximately what percentile?

84th 95th 98th 99.9th