Cognitive Reflection Test Cognitive Reflection Reflective Reasoning Under Uncertainty 2

Question 1

A man buys a horse for $60, sells it for $70, buys it back for $80, and sells it again for $90. What is his profit?

Accepted Answer

$20

Answer

He makes $10 profit on the first transaction and $10 on the second, for a total profit of $20.

Question 2

A clock shows 3:15. What is the angle between the hour and minute hands?

Accepted Answer

7.5 degrees

Answer

At 3:15 the minute hand is at 90°; the hour hand has moved 7.5° past 90° (15 min × 0.5°/min), so the angle is 7.5°.

Question 3

If you double a paper 42 times, approximately how thick is it compared to the distance from Earth to the Moon?

Accepted Answer

Much thicker

Answer

Doubling paper 42 times yields 2^42 × 0.1mm ≈ 440,000 km, which is thicker than the ~384,400 km Earth-Moon distance.

Question 4

What is the next number in the sequence: 2, 6, 12, 20, 30, __?

Accepted Answer

42

Answer

The differences are 4, 6, 8, 10, 12 — so the next number is 30 + 12 = 42.

Question 5

A father is 4 times as old as his son. In 20 years, he will be twice as old. How old is the son now?

Accepted Answer

10 years old

Answer

Let son = x; father = 4x. In 20 years: 4x+20 = 2(x+20) → 4x+20 = 2x+40 → x = 10.

Cognitive Reflection Test Practice Test