Difficulty: Easy
Correct Answer: BNQQDBS
Explanation:
Introduction / Context:
This is a standard Caesar cipher type problem where each letter in the original word is shifted by the same fixed number of places in the alphabet. We are told that "SYSTEM" becomes "RXRSDL", and we must apply the same shift to "CORRECT".
Given Data / Assumptions:
Concept / Approach:
We compare each pair of corresponding letters from SYSTEM and RXRSDL to find the amount and direction of the shift. Once we confirm that the same shift is applied to every letter, we can apply this shift to "CORRECT" letter by letter.
Step-by-Step Solution:
Step 1: Compute the shift for SYSTEM → RXRSDL.
S (19) → R (18): −1.
Y (25) → X (24): −1.
S (19) → R (18): −1.
T (20) → S (19): −1.
E (5) → D (4): −1.
M (13) → L (12): −1.
Every letter is shifted one position backward in the alphabet.
Step 2: Apply the same shift to CORRECT.
C (3) → B (2).
O (15) → N (14).
R (18) → Q (17).
R (18) → Q (17).
E (5) → D (4).
C (3) → B (2).
T (20) → S (19).
Step 3: Combine the coded letters in order.
CORRECT → B N Q Q D B S → "BNQQDBS".
Verification / Alternative check:
Reapply the −1 shift to SYSTEM to ensure we reconstruct RXRSDL. Doing this confirms that the pattern is consistent and that we have correctly identified the cipher.
Why Other Options Are Wrong:
The other options differ in one or more positions from the required sequence BNQQDBS. For example, any option that changes the positions of Q or D breaks the constant −1 shift rule and therefore cannot be correct.
Common Pitfalls:
One common mistake is to shift forward instead of backward, giving codes like DTSS... instead of RXRS... Another is to miscalculate letter positions for letters near the start or end of the alphabet.
Final Answer:
Using the same backward shift of one letter, "CORRECT" is written as BNQQDBS in that code.
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