The document discusses the profit volume (P.V.) ratio, which measures the rate of change in profit from a change in sales volume. The P.V. ratio is used to determine the break-even point, profit at different sales volumes, and sales needed to achieve a target profit. It remains constant as long as unit price and variable costs stay fixed. The P.V. ratio helps with pricing, product analysis, and profit planning. It allows businesses to calculate contribution, variable costs, margin of safety, and profit or loss at any sales level. Maintaining a high P.V. ratio is desirable as it leads to greater profits.