Word formation – With letters T, P, S, I (no repetition), how many meaningful 4-letter English words can be formed using each letter exactly once?

Introduction / Context:
We must count all 4-letter dictionary words that can be made from T, P, S, I using each letter once. Short anagram sets like this often yield a small cluster of very common words that you should memorize for speed in competitive exams.

Given Data / Assumptions:

• Available letters: {T, P, S, I}.
• Use all letters; no repetition.
• Restrict to standard English words (no abbreviations, no proper nouns).

Concept / Approach:
Try building words that are familiar regardless of order. Three widely accepted words emerge: “TIPS,” “PITS,” and “SPIT.” Re-arrangements like “SIPT,” “PSIT,” or “STIP” are typically not counted as standard standalone words in general reasoning keys. Therefore the total is three.

Step-by-Step Solution:
Construct candidates: TIPS (valid), PITS (valid), SPIT (valid).Eliminate nonwords or rare forms not generally accepted by exam keys.Hence, count = 3.

Verification / Alternative check:
Dictionary cross-check: “tips” (plural noun/verb), “pits” (plural noun/verb), “spit” (verb/noun). All three are unambiguous everyday words. Keys for alphabet-test questions consistently accept these.

Why Other Options Are Wrong:

• One/Two: Under-count; at least three clear words exist.
• Four/Five: Over-count by attempting to include nonstandard or rarely accepted forms.

Common Pitfalls:
Counting duplicates by re-ordering letters without creating a new word meaning, or admitting abbreviations. Stick to commonly recognized dictionary entries.

Final Answer:
Three