Question

A school schedules four classes-Math, Physics, Chemistry, and Biology-in four time slots (9 AM, 10 AM, 11 AM, 12 PM). Math is not at 9 AM. Chemistry is immediately before Physics. Biology is not at 12 PM, which class is at 9 AM?

• A. Math
• B. Physics
• C. Chemistry
• D. Biology
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Hint:

For follow-up scheduling questions, use previous valid arrangements to quickly identify consistent slot assignments.

Answer 1

The Correct Option is D

- Step 1: Recall constraints. Math not at 9 AM. Chemistry immediately before Physics. Biology not at 12 PM.
- Step 2: Use solution from Question 11. From Question 11, one valid arrangement is: 9 AM-Biology, 10 AM-Chemistry, 11 AM-Physics, 12 PM-Math.
- Step 3: Verify constraints. Math not at 9 AM (satisfied), Chemistry before Physics (10 AM, 11 AM), Biology not at 12 PM (satisfied).
- Step 4: Check other arrangements. Chemistry at 9 AM, Physics at 10 AM: 11 AM-Biology, 12 PM-Math. Valid. Chemistry at 11 AM, Physics at 12 PM: 9 AM-Biology, 10 AM-Math. Valid. In both, 9 AM is Biology.
- Step 5: Final conclusion. Option (4) Biology is the correct answer, as 9 AM is consistently Biology.
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