To compute ΣX², what steps are involved?

To compute ΣX², what steps are involved?

• A. Square each X value, multiply by its frequency, then sum
• B. Square the sum of X values
• C. Multiply X by frequency and sum
• D. Sum X values

Answer: (A)

To compute ΣX² you square each data value and then add up those squared values. When you have a frequency distribution, you weight each squared value by how often that value occurs, which means you multiply the squared value by its frequency and then sum across all values. For example, if 2 occurs twice, 3 occurs once, and 5 occurs once, you’d calculate 2×(2²) + 1×(3²) + 1×(5²) = 2×4 + 9 + 25 = 42. This matches the idea of summing the squares of each observation, not squaring the total sum, not just multiplying values by frequency, and not summing the raw values.

To compute ΣX² you square each data value and then add up those squared values. When you have a frequency distribution, you weight each squared value by how often that value occurs, which means you multiply the squared value by its frequency and then sum across all values.

For example, if 2 occurs twice, 3 occurs once, and 5 occurs once, you’d calculate 2×(2²) + 1×(3²) + 1×(5²) = 2×4 + 9 + 25 = 42.

This matches the idea of summing the squares of each observation, not squaring the total sum, not just multiplying values by frequency, and not summing the raw values.