In the study of probability theory, the central limit theorem (CLT) states that the distribution of sample means approximates a normal distribution. The average is a result of common characteristic within the group. As a general rule, sample sizes equal to or greater than 30 are deemed sufficient for the CLT to hold, anything less - ie; daily d=20 x 1ph may mean less cars ) it becomes a general rule, where sample sizes equal to or greater than 30 are deemed sufficient for the CLT to hold
