Question 25
Peter has seven different books on different subjects to arrange on a single shelf. He does not want to place the Physics book next to the Biology one and the Geometry book next to the Chemistry one. In how many ways can he arrange all seven books?
Interpretation: Both restrictions must hold separately: Physics is not adjacent to Biology, and Geometry is not adjacent to Chemistry. Left-to-right orders are distinct.
Answer format: enter the integer answer without units. Leading zeros are optional; the original paper uses four-digit boxes.
Interpretation: Both restrictions must hold separately: Physics is not adjacent to Biology, and Geometry is not adjacent to Chemistry. Left-to-right orders are distinct.
Answer format: enter the integer answer without units. Leading zeros are optional; the original paper uses four-digit boxes.