Which symbol is commonly used to denote the sum of all observations?

Which symbol is commonly used to denote the sum of all observations?

• A. Σ
• B. μ
• C. x̄
• D. N

Answer: (A)

The sum of all observations is denoted by the summation symbol, Σ. This symbol tells you to add up every value in a set, often written as Σ x_i to mean x_1 + x_2 + ... + x_n. The other symbols have different roles: μ represents the population mean, x̄ represents the sample mean, and N denotes the number of observations. Using Σ emphasizes the total sum, not the average or the count, which is why it is the correct notation for the sum.

The sum of all observations is denoted by the summation symbol, Σ. This symbol tells you to add up every value in a set, often written as Σ x_i to mean x_1 + x_2 + ... + x_n. The other symbols have different roles: μ represents the population mean, x̄ represents the sample mean, and N denotes the number of observations. Using Σ emphasizes the total sum, not the average or the count, which is why it is the correct notation for the sum.