Civil Services Prep

Prelims 2022 · CSAT / Logical Reasoning · Question 4

What is the value of X in the sequence 20, 10, 10, 15, 30, 75, X?

  1. 105
  2. 120
  3. 150
  4. 225

Answer

225

Pattern check: The multipliers are (\div 2, \times 1, \times 1.5, \times 2, \times 2.5). So the next step should be (\times 3). Hence, (75 \times 3 = 225).

Option-wise:

  • (a) 105: Does not fit the increasing multiplier pattern. Incorrect.
  • (b) 120: Would imply multiplier (1.6), inconsistent with the sequence. Incorrect.
  • (c) 150: Would imply multiplier (2), but the pattern requires (3). Incorrect.
  • (d) 225: Matches the next multiplier (\times 3). Correct.
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