Logical Deduction Puzzles Flashcards

Five servers (A–E) are ranked by speed. A is faster than C. C is faster than E. B is faster than A. D is faster than B. Which server is the fastest?

Answer: D

The chain D > B > A > C > E makes D the fastest.

All backup files are compressed. Some compressed files are encrypted. Which conclusion is definitely true?

Answer: Some backup files may be encrypted

Because only some compressed files are encrypted, backup files may or may not be encrypted.

In a sequence: 2, 5, 11, 23, 47, __. What is the next number?

Answer: 95

Each term is (previous × 2) + 1, so 47 × 2 + 1 = 95.

If no programmers are accountants, and all accountants are managers, which statement must be true?

Answer: No programmers are managers

Since programmers and accountants share no members, and managers here come from accountants only, no programmers are managers—but only in this closed-set reading; the safest supported conclusion is that no programmers are accountants.

A logic gate outputs 1 only when both inputs are 0. What type of gate is this?

Answer: NOR

A NOR gate outputs 1 only when all inputs are 0.

Three switches control three lights. After one test flip you determine which switch controls which light. How many test flips are needed at minimum with a deductive strategy?

Answer: 1

Using a warm/cool deduction trick (leave one on, one warm, one off) you can identify all three with one round of flips.

If A → B and B → C, and we know A is true, what can we conclude?

Answer: C is true

By hypothetical syllogism, A → C; since A is true, C must be true.