The correct answers are: Changes in stock levels are ignored; A change in the selling price per unit will alter the slope of the line on a P/V chart; An assumption is made that variable costs per unit are the same at all levels of output.

CVP analysis assumes that sales = production (ie that there is no change in stock levels) and that variable costs per unit are the same over the relevant range. However, a change in the estimate of those variable costs per unit over the whole range will change the slope of the line on a P/V chart. A change in the estimate of fixed costs will not alter the slope of the line, but will change the point of intersection with the vertical axis. It is possible to analyse more than one product using a breakeven chart, but only if the sales mix is the same over the relevant range.