2023-06-30

Average

• $$\bar{x} = \frac{\sum{x}}{n}$$
• Suppose a new number $a$ is added to a set of numbers with mean of $\bar{x}$ $$\bar{x}_{new} = \frac{n\times\bar{x} + a}{n+1}$$
• Suppose a number of value $a$ is removed from a set of numbers with mean of $\bar{x}$ $$\bar{x}_{new} = \frac{n\times\bar{x} - a}{n-1}$$