Which of the Following Is Not an Assumption About the Data

Which of the following is not an assumption about the data when using CVP analysis?

A) All costs can be easily and accurately separated into fixed and variable components.
B) Total fixed costs remain at a constant level and variable costs per unit remain unchanged at all sales levels.
C) More inventory is purchased than sold.
D) A linear relationship exists between variable costs and sales activity over the relevant range of interest.