Store A and Store B in a residential complex supply eggs in cartons of two sizes: six-egg cartons and twelve-egg cartons. Both stores charge the same amount of money for each six-egg carton, and both charge the same amount for each twelve-egg carton. Both stores have a smaller per-egg profit margin for twelve-egg cartons compared to the margin for six-egg cartons. In a certain month, the total profits from egg sales were the same for the two stores. Which store sold more eggs in that month?We are given that:
• the profit per egg is higher for six-egg cartons than for twelve-egg cartons.
• for a certain month, the total profits from egg sales were the same for the two stores.
The question asks which store sold more eggs in that month.
For fixed total profit and fixed profit per egg for each type of carton, the store with a higher proportion of twelve-egg cartons must sell more eggs overall. Intuitively, twelve-egg cartons bring less profit per egg, so a store that relies more on twelve-egg cartons must move more total eggs to reach the same total profit.
(1) In that month, the proportion of twelve-egg cartons sold in relation to six-egg cartons sold was greater for Store B than for Store A.
This means Store B’s mix is more heavily weighted toward the lower-margin twelve-egg cartons. Its average profit per egg is therefore lower than Store A’s. Since total profit is the same for both stores, the only way for Store B to match Store A’s profit with a lower profit per egg is to sell more eggs. So Store B sold more eggs. Sufficient.
(2) In that month, both stores sold about the same number of cartons of eggs.
This is vague. Even if we interpret it as “the same total number of cartons,” it still does not tell us how many of those cartons were six-egg versus twelve-egg for each store. You can construct scenarios consistent with the stem and statement (2) where Store A sells more eggs and others where Store B sells more eggs. Not sufficient.
Answer: A.