Mensa IQ Logical Deduction Problems Flashcards

Six people sit in a circle. Person A sits opposite Person D. Person B sits to the right of A. Who sits to the left of D?

Answer: The person opposite B

In a 6-person circle, opposite means 3 seats away. A is opposite D. B is to A's right. The person to D's left would be opposite to the person to A's right (B). So the person to D's left sits opposite B.

If no X are Y, and all Z are X, what follows?

Answer: No Z are Y

Since all Z are X, every Z belongs to the X category. Since no X are Y, no members of X (including all Z) can be Y. Therefore no Z are Y. This is a valid categorical syllogism.

A die shows 6 on top. What number is on the bottom?

Answer: 1

On a standard die, opposite faces always sum to 7. If 6 is on top, the bottom must be 7 - 6 = 1. This holds for all faces: 1-6, 2-5, 3-4 are the opposite pairs.

If Monday comes after Sunday, and the day after tomorrow is Monday, what day is today?

Answer: Saturday

If the day after tomorrow is Monday, then tomorrow is Sunday, and today is Saturday. Working backwards: Monday minus 2 days = Saturday.

In a group, 60% like tea, 40% like coffee, and 15% like both. What percentage likes neither?

Answer: 15%

Using the inclusion-exclusion principle: Tea∪Coffee = 60% + 40% - 15% = 85%. Those who like neither = 100% - 85% = 15%. The overlap of 15% must be subtracted to avoid double-counting.

If all squares are rectangles, and all rectangles are parallelograms, which statement is FALSE?

Answer: All parallelograms are squares

'All parallelograms are squares' is false because while all squares are parallelograms (via the chain square→rectangle→parallelogram), not all parallelograms are squares. Many parallelograms lack the equal-sides and right-angles properties of squares.