Direction: Find the missing series?

13, 37, 109, 325, ?

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RRB Clerk Prelims Memory Based Paper (Held On: 17 August 2024 Shift 2)
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  1. 935
  2. 973
  3. 485
  4. 328
  5. 970

Answer (Detailed Solution Below)

Option 2 : 973
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Detailed Solution

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Calculation:

37 - 13 = 24

109 - 37 = 72

325 - 109 = 216

The differences between consecutive terms are 24, 72, and 216.

Notice that each difference is a multiple of 24:

72 = 24 × 3

216 = 24 × 9

The next difference should be 24 × 27 = 648 (since 3² = 9 and 3³ = 27).

Now, add this difference to the last number in the series:

325 + 648 = 973

∴ The missing term in the series is 973.

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