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.
Customer lifetime value (CLV) estimates:
A firm launches a cheaper version of its best-selling product. Total sales rise slightly, but sales of the original fall sharply. What has happened?
The law of diminishing marginal returns states that:
The Laffer curve illustrates that:
Under IAS 16, which cost should be included in the cost of a new machine?
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 product sells for €38 per unit with a variable cost of €30 per unit. Fixed costs are €16 000 per month. How many units Q must be sold per month to make a profit of €6 000?
A company sells two products. Product A sells for €17 with a variable cost of €12; product B sells for €42 with a variable cost of €30. They sell in a fixed mix of 3 units of A for every 2 of B. Fixed costs are €15 600 per month. Find the total number of units Q (A and B together) needed to break even.
Answer: A · The total net profit expected from a customer over the whole relationship
CLV combines purchase frequency, margin, retention and duration (often discounted), guiding acquisition and retention spending.
Answer: D · Cannibalisation of the original product's sales
Cannibalisation occurs when a new offer mainly takes sales from the firm's existing products. It is a problem if the new product has a lower margin.
Answer: A · Adding more of a variable input to a fixed input eventually lowers the extra output per unit added
In the short run, with at least one fixed factor, marginal product eventually falls, which makes marginal cost rise.
Answer: A · Beyond some point, raising tax rates can reduce total tax revenue
Very high rates discourage taxed activity or encourage avoidance, so revenue peaks at some rate between 0 and 100%; where that peak lies is debated.
Answer: D · Installation costs needed to get it working
Purchase price plus directly attributable costs, such as delivery and installation, are capitalised. Training, later repairs and general overheads are expensed.
Answer: C · 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: Q = 2750 units
Cost-volume-profit: each unit sold earns a contribution margin, price minus variable cost per unit. Profit = Q·(p − v) − F, where F is the fixed cost. At the break-even point profit is zero, so Q = F/(p − v).
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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