Logical Reasoning Flashcards

A customer's account balance decreases by 15% and then increases by 15%. What is the net percentage change?

Answer: -2.25%

Starting at 100, after −15% the balance is 85; after +15% of 85 it becomes 97.75, a net loss of 2.25%.

If P implies Q and Q implies R, which statement must be true?

Answer: P implies R

By the transitivity of implication, if P→Q and Q→R, then P→R.

Five candidates scored 72, 85, 68, 91, and 74. What is the median score?

Answer: 74

Sorted in order: 68, 72, 74, 85, 91; the middle (third) value is 74.

Which statement best captures the meaning of: 'All that glitters is not gold'?

Answer: Appearances can be deceiving

The proverb warns that something attractive on the surface may not be genuinely valuable, i.e., appearances can be deceiving.

A password must begin with the digits '123' followed by exactly 2 letters. How many valid passwords are there?

Answer: 676

There are 26 choices for each of the 2 letter positions, giving 26 × 26 = 676 combinations.

A statement that can be simultaneously true and false violates which law of logic?

Answer: Law of Non-Contradiction

The Law of Non-Contradiction states that a proposition cannot be both true and false at the same time.

Tom ranks 5th from the top and 8th from the bottom in his class. How many students are in the class?

Answer: 12

Total students = (rank from top) + (rank from bottom) − 1 = 5 + 8 − 1 = 12.