Series Completion: Finding the Missing Term D29

Understanding series completion questions requires identifying the underlying pattern in both the alphabetical and numerical components of the given sequence. Let's carefully analyze the provided series: T9, V13, X17, Z21, B25, ? to find the missing term.

Analyzing the Alphabetical Pattern

Let's observe the progression of the letters in the series:

• T to V: Moving from T to V (T → U → V), there is a gap of one letter (U), meaning an increment of 2 positions in the alphabet.
• V to X: Moving from V to X (V → W → X), there is a gap of one letter (W), meaning an increment of 2 positions.
• X to Z: Moving from X to Z (X → Y → Z), there is a gap of one letter (Y), meaning an increment of 2 positions.
• Z to B: After Z, the alphabet wraps around. So, Z → A → B also represents an increment of 2 positions.

From this analysis, it is clear that each subsequent letter in the series is advanced by 2 positions in the alphabetical order, with the alphabet looping from Z back to A. Following this alphabetical pattern, the next letter after B will be:

• B → C → D

So, the alphabetical part of the missing term is D.

Analyzing the Numerical Pattern

Now, let's examine the progression of the numbers in the series:

• 9 to 13: The difference is $13 - 9 = 4$. So, $9 + 4 = 13$.
• 13 to 17: The difference is $17 - 13 = 4$. So, $13 + 4 = 17$.
• 17 to 21: The difference is $21 - 17 = 4$. So, $17 + 4 = 21$.
• 21 to 25: The difference is $25 - 21 = 4$. So, $21 + 4 = 25$.

This shows a consistent pattern where each subsequent number is obtained by adding 4 to the previous number. Following this numerical pattern, the next number after 25 will be:

• $25 + 4 = 29$

So, the numerical part of the missing term is 29.

Complete Missing Term

By combining both the alphabetical pattern (D) and the numerical pattern (29), the complete missing term in the sequence is D29.

Therefore, the correct option that completes the series is D29.