Question

If ORBIT is coded BEOVG, then how is PLANET coded? /

1. CYNARG

2. CONAVG

3. CYNAVG

4. XONARG
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Answer 1

1. CYNARG

Explanation:

This a example of Caesar's Cipher, in which each letter in the original word leads to a ciphered letter according to the following equation:

`C = (P + o) \text{mod} 26`

In which C is the index of the Ciphered letter in the alphabet, P is the index of the original letter and o is the offset.

Finding the offset:

O is coded B

O is the 15th letter in the alphabet, so
`P = 15`.

B is the 2nd letter in the alphabet, so
`C = 2`

`C = (P + o) \text{mod} 26`

`2 = (15 + o) \text{mod} 26`

`|o = |2-15| \text{mod} 26`

`o = 13`

So

`C = (P + 13) \text{mod} 26`

PLANET:

P

P is the 16th letter in the alphabet.

`C = (16 + 13) \text{mod} 26 = 3`

So P is coded C.

L

L is the 12th letter in the alphabet:

`C = (12 + 13) \text{mod} 26 = 25`

L is coded Y(25th letter in the alphabet)

A

A is the 1st letter in the alphabet

`C = (1 + 13) \text{mod} 26 = 14`

A is coded N

N

N is the 14th letter in the alphabet

`C = (14 + 13) \text{mod} 26 = 1`

N is coded A

E

E is the 5th letter in the alphabet

`C = (5 + 13) \text{mod} 26 = 18`

E is coded R

So the correct answer is:

1. CYNARG