Constrainted word formation – From the letters A, L, E, P, how many meaningful 4-letter English words can be formed that begin with “P” (use each letter at most once, no repetition)?
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AOne
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BTwo
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CThree
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DFour
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EFive
Answer
Correct Answer: Three
Explanation
Introduction / Context:This alphabet-test variant adds an extra constraint: the valid words must begin with a specific letter. We are given letters A, L, E, P and must count how many 4-letter meaningful English words start with “P,” using available letters without repeating any letter.
Given Data / Assumptions:
- Letters available: A, L, E, P.
- Word length = 4; begin with “P.”
- No letter repetition.
Concept / Approach:Construct “P _ _ _” using remaining letters {A, L, E} in some order. The well-known valid words are “PALE,” “PEAL,” and “PLEA.” All three are standard English words: PALE (light color; lacking color), PEAL (a loud ringing of bells), PLEA (request; legal assertion). No other distinct 4-letter arrangement starting with P and using A/L/E exactly once yields additional standard words beyond these three.
Step-by-Step Solution:Enumerate: PALE, PELA (no), PEAL, PELA (dup/nonstandard), PLEA.Confirm dictionary status for PALE, PEAL, PLEA.Count = 3.
Verification / Alternative check:Cross-check via a trusted dictionary or word list; all three appear commonly and are frequently used in exams of this type.
Why Other Options Are Wrong:
- One/Two: Under-count; ignore one or more of the valid triplet.
- Four/Five: Over-count; would require accepting nonstandard or duplicated arrangements.
Common Pitfalls:Overlooking “PLEA,” which is very common in legal and general contexts. Always verify each candidate begins with P and uses letters without repetition.
Final Answer:Three