Difficulty: Easy
Correct Answer: ₹ 75
Explanation:
Introduction / Context: Changing from an 8% loss to an 8% profit is a total swing of 16 percentage points on the cost price. The rupee change in outcome (₹12) therefore equals 16% of the cost. This “swing method” is a fast technique for many profit–loss questions where two scenarios differ only by percentage on the same base.
Given Data / Assumptions:
Concept / Approach: The change from −8% to +8% is a net change of 16% of cost. Therefore 0.16 * Cost = ₹12. Solve for the cost to get a neat integer. No selling price needs to be computed explicitly.
Step-by-Step Solution:
Let C be cost price.Net swing = 8% + 8% = 16% = 0.16 of C.Given swing equals ₹12 ⇒ 0.16C = 12.C = 12 / 0.16 = 12 * (100/16) = 1200/16 = ₹75.Verification / Alternative check: At C = 75: 8% loss ⇒ loss = ₹6 ⇒ SP = 69. 8% profit ⇒ profit = ₹6 ⇒ SP = 81. Difference in outcomes = 81 − 69 = ₹12, matching the given.
Why Other Options Are Wrong: ₹72, ₹70, ₹80, ₹60 would yield swings of 11.52, 11.2, 12.8, and 9.6 respectively, not ₹12.
Common Pitfalls: Applying the 16% swing to selling price rather than cost. The swing is always on the same base as the stated percentages, here the cost price.
Final Answer: ₹ 75
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