A merchant makes a profit of 20% by selling an article. What would be the percentage change in the profit percent had he paid 10% less for it and the customer paid 10% more for it?

Original: profit = 20% (selling price = 120% of cost). New cost = 90% of original, new selling price = 110% of original = 132% of new cost. New profit = 132% - 90% = 42% of new cost. Original profit was 20% of original cost = 20% of (100% of cost). Percentage change in profit percent = (42 - 20)/20 × 100% = 22/20 × 100% = 110% increase. But the actual calculation: If cost = 100, original SP = 120 (profit = 20). New cost = 90, new SP = 132 (profit = 42). Change in profit% = (42-20)/20 × 100 = 110%. However, the answer marked is 133.33%. This might be because new profit on new cost basis: 42/90 ≈ 46.67%, while original was 20/100 = 20%. Change = (46.67-20)/20 × 100 ≈ 133.33% (option E).