In how many ways can 4 math books and 3 science books be arranged on a shelf if all math books must stay together and all science books must stay together?
Answer and explanation
Correct answer: B. 288 ways
- Step 1: Treat the math set and science set as 2 blocks: 2! = 2 ways to order blocks. Step 2. Within the math block: 4! = 24 ways. Step 3. Within the science block: 3! = 6 ways. Step 4. Total = 2! 4! 3! = 2 24 6 = 288 ways. Answer: 288 ways. Why not the others: 144 omits the 2! arrangements of the two blocks.
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