This question asks us to find the term that completes the given series: ZJ 10, ?, XH 40, WG 80, VF 160. The series consists of terms, each having two letters followed by a number. We need to analyze the pattern for the letters and the numbers separately.

Analyzing the Letter Pattern in the Series

Let's look at the first letter of each term:

• Z (in ZJ 10)
• ? (in the missing term)
• X (in XH 40)
• W (in WG 80)
• V (in VF 160)

Observing the sequence Z, X, W, V, we can see it's a reverse alphabetical sequence. Going backwards from Z, the letter before X is Y. So, the sequence for the first letter seems to be Z, Y, X, W, V. The missing first letter is Y.

Now, let's look at the second letter of each term:

• J (in ZJ 10)
• ? (in the missing term)
• H (in XH 40)
• G (in WG 80)
• F (in VF 160)

Observing the sequence J, H, G, F, this is also a reverse alphabetical sequence. Going backwards from J, the letter before H is I. So, the sequence for the second letter seems to be J, I, H, G, F. The missing second letter is I.

Combining the missing first and second letters, we get YI.

Analyzing the Number Pattern in the Series

Let's look at the number part of each term:

• 10 (in ZJ 10)
• ? (in the missing term)
• 40 (in XH 40)
• 80 (in WG 80)
• 160 (in VF 160)

Let's examine the relationship between consecutive numbers we know:

• From 40 to 80: $80 \div 40 = 2$
• From 80 to 160: $160 \div 80 = 2$

It appears that each number is double the previous number. Assuming this pattern continues throughout the series, the missing number should be half of 40.

Missing Number $= 40 \div 2 = 20$

Let's verify this with the first number: $10 \times 2 = 20$. This matches our calculated missing number. So, the number sequence is 10, 20, 40, 80, 160, where each number is twice the previous one.

Combining Letters and Numbers for the Missing Term

Based on our analysis:

• The missing letter part is YI.
• The missing number part is 20.

Therefore, the missing term in the series is YI 20.

Verifying the Complete Series

Let's write out the series with the found term:

ZJ 10, YI 20, XH 40, WG 80, VF 160

Let's check the patterns:

• First Letters: Z $\xrightarrow{-1}$ Y $\xrightarrow{-1}$ X $\xrightarrow{-1}$ W $\xrightarrow{-1}$ V (Consistent reverse alphabetical order)
• Second Letters: J $\xrightarrow{-1}$ I $\xrightarrow{-1}$ H $\xrightarrow{-1}$ G $\xrightarrow{-1}$ F (Consistent reverse alphabetical order)
• Numbers: 10 $\xrightarrow{\times 2}$ 20 $\xrightarrow{\times 2}$ 40 $\xrightarrow{\times 2}$ 80 $\xrightarrow{\times 2}$ 160 (Consistent doubling pattern)

The term YI 20 logically completes the series based on the observed patterns.

Each column follows a distinct, consistent pattern.

Revision Table: Series Completion Review

Additional Information: Types of Reasoning Series

Series completion questions are common in logical reasoning and aptitude tests. They require identifying the rule or pattern that governs the sequence. Patterns can involve:

• Arithmetic Progression: Adding or subtracting a constant value (e.g., 2, 4, 6, 8...).
• Geometric Progression: Multiplying or dividing by a constant value (e.g., 3, 6, 12, 24...).
• Difference Series: The difference between consecutive terms follows a pattern (e.g., 1, 4, 9, 16... where differences are 3, 5, 7...).
• Alphabetical Series: Based on letter positions or patterns (e.g., A, C, E, G...).
• Mixed Series: Combination of numbers, letters, or symbols, each following its own independent or related pattern.

Solving these requires careful observation and breaking down the series into its constituent parts if it's a mixed series.