UPSC CSE 2025 · PYQ · Number Series · medium
What is X in the sequence 24, X, 12, 18, 36, 90?
- A.18
- B.12✓ Correct
- C.9
- D.6
The pattern involves multiplying by successive half-integers: each term equals the previous term multiplied by (0.5, 1, 1.5, 2, 2.5). Checking: 24 × 0.5 = 12 (X); 12 × 1 = 12; 12 × 1.5 = 18; 18 × 2 = 36; 36 × 2.5 = 90. Thus X = 12.
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