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Question

Select the alphanumeric-cluster that can replace the question mark (?) in the following series.

A9B, C49D, E121F, ?

This question was previously asked in
RRB NTPC 2019 CBT 1 Question Paper (8-Mar-2021) (Shift 2)
The correct answer is
G225H

Alphanumeric Series Pattern Analysis

The given series is: A9B, C49D, E121F, ?

We need to identify the pattern governing the letters and numbers separately.

Letter Pattern

  • First Letter: The first letters follow an alphabetical sequence, skipping one letter each time: A, C, E. The next letter should be G.
  • Last Letter: The last letters also follow an alphabetical sequence, skipping one letter: B, D, F. The next letter should be H.

Number Pattern

The numbers in the series are 9, 49, 121.

  • Observe that these numbers are perfect squares:
    • $9 = 3^2$
    • $49 = 7^2$
    • $121 = 11^2$
  • Now, look at the bases of these squares: 3, 7, 11.
  • The difference between consecutive bases is constant: $7 - 3 = 4$ and $11 - 7 = 4$.
  • Therefore, the next base in the sequence should be $11 + 4 = 15$.
  • The next number in the series will be the square of 15: $15^2 = 225$.

Identifying the Missing Term

Combining the patterns identified:

  • The next first letter is G.
  • The next number is 225.
  • The next last letter is H.

Thus, the alphanumeric cluster that replaces the question mark is G225H.

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Similar Questions

  1. Which of the following letter-number clusters will replace the question mark (?) in the given series to make it logically complete?
    GBD 14, KFH 17, OJL 20, SNP 23, ?
  2. Which of the following letter-number clusters will replace the question mark (?) in the given series to make it logically complete?
    KFU-15 IIQ-22 GLM-31 EOI-42 ?
  3. Which of the following letter-number clusters will replace the question mark (?) in the given series to make it logically complete?

    HYP 8, LCT 15, PGX 29, TKB 57, XOF 113, ?
  4. Which option will replace the question mark in the below series?
    A25 : Y1 :: L14 : ?
  5. Select the option that can replace the question mark (?) in the given series.

    P3L, N5N, L7P, J11R, H13T, ?
  6. Select the set that can replace the question marks (?) in the following series.

     $\displaystyle \frac{\text{D}}{23} \; \frac{20}{\text{G}} \; \frac{\text{J}}{17} \; \frac{14}{\text{M}} \; \frac{\text{P}}{11} \; \frac{\text{?}}{\text{?}}$

  7. Select the term that can replace the question mark (?) in the following series.

    B3, D10, F17, H24, ?
  8. Select the alphanumeric-cluster that can replace the question mark (?) in the following series.

    B4D, C9I, D16P, ?
  9. Four letter-pairs have been given, out of which three are alike in some manner and one is different. Select the odd one.
  10. Study the given series carefully and select the option that will come next (in place of the question marks).

    $\frac{\text{C}}{29} \frac{25}{\text{F}} \frac{\text{I}}{21} \frac{17}{\text{L}} \frac{\text{O}}{13} \frac{\text{?}}{\text{?}}$

Important Questions from Letter and Number Based

  1. Select the option in which the numbers are related in the same way as are the numbers of the following set.

    (4, 8, 16)

  2. Select the option that is related to the third number in the same way as the second number is related to the first number.

    23 : 441 : : 28 : ?

  3. Select the option that is related to the third number in the same way as the second number is related to the first number and the sixth number is related to the fifth number.

    12 : 72 ∷ 18 : ? ∷22 : 242
  4. Select the option that is related to the third number in the same way as the second number is related to the first number.

    7 : 56 :: 11 : ?

  5. Select the option in which the numbers are related in the same way as are the numbers of the following set.

    (12, 60, 84)

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