A dishonest seller takes money for 250 g of soap and delivers only 220 g. What percentage gain does he make?
Explanation
Use actual quantity delivered and money received to form effective cost and selling values before finding profit percent. For this question, identify every monetary base before applying a percentage. The question-specific working supplied in the record is: Gain% = ((Claimed weight − Actual weight) / Actual weight) × 100 = ((250 − 220) / 220) × 100 = 13.64%. Profit and loss questions become unreliable when a percentage is applied to the wrong base. If several changes occur, convert each change into a multiplier and apply them in order. The distractors 12.64%, 17.64%, 13.64% 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. 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.