Introduction
In aptitude exams, sometimes articles are sold through successive transactions, where a profit or loss is made more than once on the same item. For example: a shopkeeper first sells an article to another trader at a profit, and that trader sells it again at another profit/loss.
These problems cannot be solved by directly adding/subtracting percentages. Instead, we apply a specific formula for successive percentages.
Pattern: Successive Profit & Loss
Pattern
If a profit/loss of x% is followed by a profit/loss of y%, the net effect is:
Net % = x + y + (x × y) / 100
Here, treat profit as positive (+) and loss as negative (-). Final result > 0 → Net profit. Final result < 0 → Net loss.
Step-by-Step Example
Question
A trader sells an article at a profit of 20%, and the next buyer sells it again at a loss of 10%. Find the overall profit or loss percentage.
Options:
- A. 8% overall profit
- B. 10% overall profit
- C. 6% overall profit
- D. No profit, no loss
Solution
-
Step 1: Identify the successive changes.
Successive changes are +20% (profit) and -10% (loss). -
Step 2: Apply the successive-percentage formula.
Net % = 20 + (-10) + (20 × -10) / 100 = 20 - 10 - 2 = +8%. -
Step 3: Interpret the result.
Positive result → 8% overall profit. -
Final Answer:
8% overall profit → Option A -
Step 4: Quick Check (verify with CP = 100).
Assume CP = 100 → after +20% = 120 → after -10% = 120 - 12 = 108 → Net = 108 - 100 = 8 → 8% profit ✅
Quick Variations
Case 1: Two successive profits (say +10% and +20%). Net % = 10 + 20 + (10×20)/100 = 32% profit.
Case 2: Two successive losses (say -10% and -20%). Net % = -10 - 20 + (-10×-20)/100 = -28% (net loss).
Case 3: One profit, one loss (say +25%, -20%). Net % = 25 - 20 + (25×-20)/100 = 25 - 20 - 5 = 0 → No overall gain/loss.
Trick to Always Use
- Use formula: Net % = x + y + (x×y)/100.
- Assign positive for profit, negative for loss.
- If unsure, assume CP = 100 and calculate step by step.
- Quickly identify: Positive = Profit, Negative = Loss.
Summary
Summary
- Use the successive-percentage formula: Net % = x + y + (x×y)/100.
- Assign + for profits and - for losses before applying the formula.
- Verify results by assuming CP = 100 and computing successive SP values.
- Interpret sign: positive → overall profit; negative → overall loss.
Example to remember:
+20% followed by -10% → Net % = 20 - 10 + (20×-10)/100 = 8% profit
