# Ten days of statistics (7) - Central limit theorem

## Central limit theorem

The central limit theorem (CLT) establishes that, in many situations, for identically distributed independent samples, the standardized sample mean tends towards the standard normal distribution even if the original variables themselves are not normally distributed.

Eventhough at first our data seems to be chaotic (1), skew to the right (2) or left (3). We can safely say that when sample size is big enough, most probability distributions will eventually becomes normal distribution.

## Practice

Hackerrank has some exercises for you to test your knowledge:

- https://www.hackerrank.com/challenges/s10-the-central-limit-theorem-1/problem
- https://www.hackerrank.com/challenges/s10-the-central-limit-theorem-2/problem
- https://www.hackerrank.com/challenges/s10-the-central-limit-theorem-3/problem

Next lesson: Correlationship