Difficulty: Medium
Correct Answer: 23.5%
Explanation:
Introduction / Context: This is a weighted-average selling price problem: a single markup followed by multiple discount tiers. The overall profit comes from the weighted mean of selling prices versus cost across all items sold.
Given Data / Assumptions:
Concept / Approach: Compute SP for each tranche and take the weighted average SP across 100 units. Overall profit% = (Average SP − Cost)/Cost * 100 with the cost base per unit fixed at 100.
Step-by-Step Solution:
Tranche A (40 units): SP_A = 140.Tranche B (30 units): SP_B = 140 * (1 − 0.145) = 140 * 0.855 = 119.7.Tranche C (30 units): SP_C = 140 * 0.75 = 105.Average SP = 0.4*140 + 0.3*119.7 + 0.3*105 = 56 + 35.91 + 31.5 = 123.41.Profit% = (123.41 − 100)/100 * 100 = 23.41% ≈ 23.5%.Verification / Alternative check: Total revenue over 100 units = 12,341; total cost = 10,000 ⇒ gain = 2,341 ⇒ 23.41%.
Why Other Options Are Wrong: 26.5%, 28.6%, and 30% overstate the weighted effect; 21% understates it.
Common Pitfalls: Averaging discount rates instead of revenue, or forgetting to weight by quantities sold at each discount tier.
Final Answer: 23.5%
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