Break-even analysis
- Contribution margin
- CM = p − v
- Break-even quantity
- QBE = FC/(p − v)
- Target profit
- Q = (FC + profit)/(p − v)
- Profit
- π = (p − v)·Q − FC
- Margin of safety
- (Q − QBE)/Q
Formula sheets, the key method steps for every topic and 8 practice problems, with full solutions at the back.
A product costs €60 and sells for €80. What is the profit margin as a percentage of the selling price?
A cinema sells small popcorn for €4 and large for €8. Adding a medium size at €7.50 makes many more people buy the large. Which effect is this?
A firm has spent €1 million on research for a product that now looks unprofitable. When deciding whether to continue, the €1 million should be:
Okun's law describes:
A company increases its allowance for doubtful receivables. What is the effect?
Machine hours are scarce. Product X earns €20 contribution and needs 4 hours; product Y earns €15 and needs 2 hours. Which should be made first?
A company sells 960 units at €28 each. The variable cost is €18 per unit and fixed costs are €8 000. Find the degree of operating leverage DOL at this sales level.
A company sells two products. Product A sells for €21 with a variable cost of €15; product B sells for €25 with a variable cost of €10. They sell in a fixed mix of 3 units of A for every 1 of B. Fixed costs are €16 500 per month. Find the total number of units Q (A and B together) needed to break even.
Answer: B · 25%
Profit = €20. Margin = €20 ÷ €80 = 25%. The mark-up on cost is €20 ÷ €60 ≈ 33%.
Answer: A · The decoy effect
A decoy is an option that is slightly worse than the target, making the target look like good value by comparison. Choices depend on the set of options shown.
Answer: B · Ignored, because it is a sunk cost
Sunk costs cannot be recovered and do not change with the decision, so rational choices compare only future costs and benefits.
Answer: D · A negative relationship between output growth and changes in unemployment
Okun observed that unemployment falls when real GDP grows faster than its trend rate and rises when growth is below trend.
Answer: D · An expense is recognised and net receivables fall
The increase is charged to profit, and the allowance is deducted from gross receivables, so the balance sheet shows the amount expected to be collected.
Answer: B · Y, because it earns €7.50 per hour versus €5 for X
X earns €20 ÷ 4 = €5 per hour, Y earns €15 ÷ 2 = €7.50 per hour. With a scarce resource, maximise contribution per scarce hour.
Answer: DOL = 6
Operating leverage: fixed costs make profit react more strongly than sales. The degree of operating leverage DOL = contribution margin/operating profit tells you that a 1% change in sales changes profit by DOL %. It is very high just above break-even and falls as sales grow.
Answer: Q = 2000 units
Break-even with a sales mix: when products sell in a fixed ratio, use the weighted average contribution margin: weight each product's p − v by its share of units. Break-even units = F/(weighted contribution margin), split again in the mix ratio.
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