A trader sells two water bottles at the same selling price. On one he gains 30% and on the other he loses 30%. Find the overall profit or loss percentage.
Explanation
The complete calculation confirms 8.0% Loss as the correct option. Calculate total cost price and total selling price for all articles before deciding the net profit or loss. For this question, identify every monetary base before applying a percentage. The question-specific working supplied in the record is: When gain% and loss% are equal and SP is same, Net Loss% = (x/10)^2. Net Loss = (30/10)^2 = 9.0%.. Profit and loss questions become unreliable when a percentage is applied to the wrong base. Profit or loss percent uses cost price, while discount percent uses marked price. If several changes occur, convert each change into a multiplier and apply them in order. The distractors 11.0% Loss, 10.0% Loss, 9.0% Loss can result from interchanging cost price and selling price, treating discount as loss, adding successive rates, ignoring quantity, or rounding before the final step. A dependable check is to assume cost price 100 whenever only percentages are involved, reconstruct the selling value, and compare the resulting ratio with the selected option. Also verify direction: profit requires selling price above cost price, whereas loss requires it below cost price. In marked-price problems, a discount can coexist with profit because marked price and cost price are different bases. This method preserves the numerical relationships in the stem and develops formula selection, percentage-base recognition and option elimination for SSC, Railway, Banking and other competitive aptitude examinations.