LSAT (Law School Admission Test)Analytical ReasoningMedium
A farmer has six fields—1, 2, 3, 4, 5, 6—arranged in a row. She plans to plant a different crop in each field: Corn, Wheat, Oats, Rye, Soy, or Barley. The planting must follow these conditions: 1. Wheat must be planted in an even-numbered field. 2. Oats must be planted immediately next to Soy. 3. Rye cannot be planted in Field 1 or Field 6. 4. Corn must be planted in a field with a lower number than Barley. 5. If Soy is planted in Field 3, then Rye must be planted in Field 5. If Corn is planted in Field 2, and Barley is planted in Field 4, which of the following must be true?
- AOats is planted in Field 1.
- BWheat is planted in Field 6.
- CSoy is planted in Field 5.
- DRye is planted in Field 3.
Show answer & explanationAnswer & explanation
Correct answer: B. Wheat is planted in Field 6.
If Corn is in Field 2 and Barley in Field 4, then Wheat must be in an even-numbered field (rule 1). Fields 2 and 4 are taken. The only remaining even-numbered field is Field 6. Therefore, Wheat must be planted in Field 6.
Why the other options are wrong
- A. If Oats is in Field 1, then Soy must be in Field 2. But Corn is in Field 2. So Oats cannot be in Field 1.
- C. If Soy is in Field 5, then Oats must be in Field 6. This is possible, but not a 'must be true'.
- D. If Rye is in Field 3, then Oats and Soy must be in Field 1 and 5 (or 5 and 1) or Field 5 and 6 (or 6 and 5). This is possible, but not a 'must be true'.
Residual Placement
Determining the position of an element by eliminating all other possible positions based on rules and prior deductions.
- Often occurs when only one valid slot remains.
- Relies heavily on exclusion and fixed positions.
- A powerful technique for 'must be true' questions.
Memory trick: Remove The Impossible, What Remains Is True.