For the data with X: 4, 3, 2, 1 and F: 1, 2, 4, 2, what is ΣX?

For the data with X: 4, 3, 2, 1 and F: 1, 2, 4, 2, what is ΣX?

• A. 10
• B. 15
• C. 20
• D. Cannot be determined from the table

Answer: (C)

When summing X across all observations, you weight each X by how often it occurs. Multiply each X value by its frequency and add those products: 4×1, 3×2, 2×4, 1×2. That gives 4, 6, 8, and 2, which sum to 20. So ΣX = 20. If you ignored frequencies, you’d just add the distinct X values (4+3+2+1 = 10), which isn’t correct for this table.

When summing X across all observations, you weight each X by how often it occurs. Multiply each X value by its frequency and add those products: 4×1, 3×2, 2×4, 1×2.

That gives 4, 6, 8, and 2, which sum to 20. So ΣX = 20.

If you ignored frequencies, you’d just add the distinct X values (4+3+2+1 = 10), which isn’t correct for this table.