# Central Limit theorem

## Central Limit theorem :

The Central Limit Theorem is a fundamental statistical principle that states that, given a sufficiently large sample size, the distribution of sample means will approach a normal distribution. This means that, even if the underlying population distribution is not normally distributed, the distribution of sample means will approximate a normal distribution as the sample size increases.
To illustrate this principle with an example, consider a population of students in a high school. The grades of these students are not normally distributed, with some students having high grades and others having low grades. However, if we take a sample of 10 students from this population and calculate the mean of their grades, the distribution of these sample means will approximate a normal distribution. This is because the Central Limit Theorem states that the distribution of sample means will approach a normal distribution as the sample size increases.
Another example of the Central Limit Theorem in action is in the field of finance. Stock prices are known to be non-normally distributed, with some stocks experiencing large price movements and others experiencing small price movements. However, if we take a sample of 100 stocks and calculate the mean of their daily returns, the distribution of these sample means will approximate a normal distribution. This is because the Central Limit Theorem states that the distribution of sample means will approach a normal distribution as the sample size increases.
The Central Limit Theorem is important because it allows us to make inferences about a population based on a sample. For instance, if we take a sample of 100 students and calculate the mean of their grades, we can use the Central Limit Theorem to estimate the mean of the entire population of students. This is because the distribution of sample means will approximate a normal distribution, and we can use this normal distribution to calculate the mean and standard deviation of the population.
Furthermore, the Central Limit Theorem allows us to use statistical tests that assume a normal distribution, such as t-tests and ANOVA tests. These tests are widely used in many fields, including psychology, biology, and finance, to make inferences about the population based on a sample. Without the Central Limit Theorem, these tests would not be valid because the distribution of sample means would not approximate a normal distribution.
In conclusion, the Central Limit Theorem is a fundamental statistical principle that states that, given a sufficiently large sample size, the distribution of sample means will approach a normal distribution. This theorem is important because it allows us to make inferences about a population based on a sample and use statistical tests that assume a normal distribution.