Practice question · Multiple choice
Heights, measurement errors and exam scores are all roughly normal. What do these have in common that produces the same curve?
Hints
- What determines a person's height? One factor, or hundreds adding up?
- The theorem is about sums. Ask what is being summed in each case.
Show the answer
B. Each is a sum of many small independent influences
Why
Height is many genes plus nutrition plus health; an exam score aggregates many items. The theorem's indifference to the underlying distributions is what makes the curve ubiquitous, and knowing the condition tells you when to expect something else: multiplicative influences give lognormal, which is why income is skewed.
Practise The Normal Distribution
The app has 6 more questions on this lesson, and keeps your place in the course. Mathematics I is free to start.