Sevinch runs a busy café near a university in Tashkent. Every month she orders paper cups from a supplier that sells them in two box sizes. A large box holds 100 cups and costs 12 dollars. A small box holds 40 cups and costs 6 dollars.
This month she needed exactly 500 cups, because her storeroom had space for no more. The supplier also had a rule: free delivery only for orders of exactly 8 boxes. The order form had two boxes to fill in: the number of large boxes and the number of small ones.
Her first idea was five large boxes: exactly 500 cups, but only 5 boxes, so she would pay for delivery. She needed both conditions at once.
She tried the numbers one by one. Two large boxes and six small ones made 8 boxes but only 440 cups. Four large boxes and four small ones made 8 boxes but 560 cups, too many for the storeroom. Three large boxes and five small ones made 8 boxes and 300 plus 200, exactly 500 cups, for 36 plus 30, or 66 dollars.
Only that order met both conditions. Each wrong order had one part right and one part wrong, and Sevinch realised that a half-right order was simply a wrong order.
Her brother, who was preparing for the GMAT, smiled when she told him. "That is a Two-Part Analysis question," he said. "Two answers, but only one decision, and no credit for getting one of them right." Sevinch added a small table of box combinations to her ordering notebook, so that next month the right answer would take a minute.