How many different arrangements of the letters of PERU are there if E and U must stay next to each other?
Answer and explanation
Correct answer: B. 12 arrangements
- Step 1: Treat E and U as one block: the block, P and R can be arranged in 3! = 6 ways.
- Step 2: Inside the block E and U can swap: 2 ways, so 6 x 2 = 12.
Answer
12 arrangements.
Why not the others: 24 ignores the restriction, 6 forgets the swap inside the block, and 8 has no counting basis.
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