Codebusters Test Codebusters Logical Puzzles and Riddles 3

Question 1

In the Caesar cipher shift-by-13 (ROT13), what does encoding 'A' give, and what does encoding the result give back?

Accepted Answer

N, then A

Answer

N, then B

Answer

M, then A

Answer

O, then A

Question 2

A sequence reads 2, 3, 5, 8, 13, 21, ... but differs from Fibonacci because the first two terms are 2 and 3. What is the 8th term?

Accepted Answer

55

Answer

34

Answer

89

Answer

144

Question 3

A lateral thinking puzzle says: 'A man walks into a bar and asks for water. The bartender pulls out a gun and points it at him. The man says thank you and leaves.' Why did the man thank the bartender?

Accepted Answer

The man had hiccups and the fright cured them

Answer

The gun was a water gun

Answer

The bartender gave him a glass of water first

Answer

The man was a robber who changed his mind

Question 4

In modular arithmetic, if a cipher maps letter position P to (3P + 7) mod 26, what does 'A' (P=0) encode to?

Accepted Answer

G

Answer

H

Answer

D

Answer

E

Question 5

A truth-teller always tells the truth and a liar always lies. You meet one person and ask 'Are you a truth-teller?' What does a liar answer?

Accepted Answer

Yes

Answer

No

Answer

I don't know

Answer

Maybe

Question 6

The word CRYPTOGRAM rearranged is an anagram of which phrase relevant to codebreaking?

Accepted Answer

ARMY GROTTO PC

Answer

OGRAMRYPT

Answer

COPY MARGRT

Answer

CRYPT GORAM

Question 7

In a Codebusters timed round, a team solves 4 problems in 20 minutes. If each subsequent problem takes 1.5× as long as the previous, and the first took 2 minutes, how long did the fourth problem take?

Accepted Answer

6.75 min

Answer

4.5 min

Answer

9 min

Answer

10.125 min