Select the option that is related to the fifth letter-cluster in the same way as the second letter-cluster is related to the first letter-cluster and the fourth letter-cluster is related to the third letter-cluster. CIVILIAN : AGREFCSF :: DOCTRINE : BMYPLCFW :: EQUATION : ?
COQWNCGF
This type of question asks us to find a relationship between two letter clusters and apply the same relationship to a new cluster to find the missing one. We are given two pairs that follow the same rule: CIVILIAN is related to AGREFCSF, and DOCTRINE is related to BMYPLCFW. We need to find the letter cluster related to EQUATION using this same rule.
Let's look at how each letter in CIVILIAN changes to become the corresponding letter in AGREFCSF. We can use the alphabetical position of each letter (A=1, B=2, ..., Z=26).
| Position | CIVILIAN | Position Value | AGREFCSF | Position Value | Difference | Pattern |
|---|---|---|---|---|---|---|
| 1 | C | 3 | A | 1 | \(1 - 3 = -2\) | \(-2\) |
| 2 | I | 9 | G | 7 | \(7 - 9 = -2\) | |
| 3 | V | 22 | R | 18 | \(18 - 22 = -4\) | \(-4\) |
| 4 | I | 9 | E | 5 | \(5 - 9 = -4\) | |
| 5 | L | 12 | F | 6 | \(6 - 12 = -6\) | \(-6\) |
| 6 | I | 9 | C | 3 | \(3 - 9 = -6\) | |
| 7 | A | 1 | S | 19 | \(19 - 1 = +18\) or \(1 - 8 = -7 \equiv 19 \pmod{26}\) | \(-8\) |
| 8 | N | 14 | F | 6 | \(6 - 14 = -8\) |
Looking at the differences, there seems to be a pattern based on the letter's position in the word. The shifts are -2, -2, -4, -4, -6, -6, -8, -8 for the 1st, 2nd, 3rd, 4th, 5th, 6th, 7th, and 8th letters respectively. When the difference is negative and wraps around the alphabet (like 1 - 8 = -7), we add 26 to find the position (e.g., -7 + 26 = 19, which is S).
Let's apply the same shift pattern (-2, -2, -4, -4, -6, -6, -8, -8) to DOCTRINE and see if we get BMYPLCFW.
| Position | DOCTRINE | Position Value | Shift | New Position Value | New Letter | BMYPLCFW |
|---|---|---|---|---|---|---|
| 1 | D | 4 | -2 | \(4 - 2 = 2\) | B | B |
| 2 | O | 15 | -2 | \(15 - 2 = 13\) | M | M |
| 3 | C | 3 | -4 | \(3 - 4 = -1 \equiv 25 \pmod{26}\) | Y | Y |
| 4 | T | 20 | -4 | \(20 - 4 = 16\) | P | P |
| 5 | R | 18 | -6 | \(18 - 6 = 12\) | L | L |
| 6 | I | 9 | -6 | \(9 - 6 = 3\) | C | C |
| 7 | N | 14 | -8 | \(14 - 8 = 6\) | F | F |
| 8 | E | 5 | -8 | \(5 - 8 = -3 \equiv 23 \pmod{26}\) | W | W |
The pattern successfully transforms DOCTRINE into BMYPLCFW. So, the identified positional shift pattern is correct.
Now we apply the same positional shift pattern (-2, -2, -4, -4, -6, -6, -8, -8) to the letter cluster EQUATION.
| Position | EQUATION | Position Value | Shift | New Position Value | New Letter |
|---|---|---|---|---|---|
| 1 | E | 5 | -2 | \(5 - 2 = 3\) | C |
| 2 | Q | 17 | -2 | \(17 - 2 = 15\) | O |
| 3 | U | 21 | -4 | \(21 - 4 = 17\) | Q |
| 4 | A | 1 | -4 | \(1 - 4 = -3 \equiv 23 \pmod{26}\) | W |
| 5 | T | 20 | -6 | \(20 - 6 = 14\) | N |
| 6 | I | 9 | -6 | \(9 - 6 = 3\) | C |
| 7 | O | 15 | -8 | \(15 - 8 = 7\) | G |
| 8 | N | 14 | -8 | \(14 - 8 = 6\) | F |
Applying the pattern to EQUATION results in the letter cluster COQWNCGF.
Let's check the generated letter cluster COQWNCGF against the given options:
The calculated result, COQWNCGF, matches Option 4.
| Concept | Description | Example (from this problem) |
|---|---|---|
| Letter Cluster Analogy | Finding a pattern between two groups of letters and applying it to a new group. | CIVILIAN:AGREFCSF as DOCTRINE:BMYPLCFW |
| Positional Shift | The shift in the letter's alphabetical position depends on its place in the word. | 1st letter shifts by -2, 3rd by -4, 5th by -6, etc. |
| Alphabetical Position | Assigning a number to each letter (A=1, B=2, ...). | C=3, I=9, V=22, etc. |
| Modular Arithmetic (for wrap-around) | When a shift goes below 'A' (1), wrapping around from 'Z' (26) by adding 26. | \(3 - 4 = -1\), which is \(25\) (Y) after adding 26. |
Letter series and analogy questions are common in reasoning tests. They require identifying the rule that connects the terms in the series or the pair of terms in the analogy. Common patterns include:
To solve these problems effectively, it's helpful to:
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