Cognitive Reflection Test Questions (With Answers Explained)
Cognitive reflection test questions are short math-style trick questions that have an obvious, fast answer that's wrong and a slower, correct answer you get by double-checking. The original test, created by Shane Frederick in 2005, has 3 questions (including the famous bat and ball problem). Researchers later added 4 more, making a 7-question version. Try them below before you peek at the answers.
If you keep falling for trick questions on tests, IQ Tester shows whether it's logic, mental math or focus that's letting you down: Find my weak spots.
What the Cognitive Reflection Test is
The Cognitive Reflection Test (CRT) measures one thing: can you stop your first instinct and check it?
Psychologists often describe two modes of thinking:
- System 1 (fast): automatic, gut-level, effortless. Great for recognizing a friend's face or catching a ball.
- System 2 (slow): deliberate, effortful, careful. What you use for a hard math problem.
The CRT is built so System 1 shouts a wrong answer. Getting it right means System 2 steps in and says "hold on." That's why it's a favorite in behavioral economics and why it goes viral on TikTok every few months.
It's not an IQ test. The math is simple. It's a test of whether you check.
The original 3 questions
Shane Frederick's cognitive reflection test, 3 questions. Grab a piece of paper. No calculator needed. Write your first answer, then your checked answer.
Question 1: the bat and ball problem
A bat and a ball cost $1.10 in total. The bat costs $1.00 more than the ball. How much does the ball cost?
Question 2: the widget machine question
If it takes 5 machines 5 minutes to make 5 widgets, how long would it take 100 machines to make 100 widgets?
Question 3: the lily pad problem
In a lake, there is a patch of lily pads. Every day, the patch doubles in size. If it takes 48 days for the patch to cover the entire lake, how long would it take for the patch to cover half the lake?
Got your answers? Don't scroll yet.
4 newer CRT questions
Researchers Maggie Toplak, Richard West and Keith Stanovich published extra CRT questions in 2014, partly because the original three had become so famous that many people already knew them. Together with the originals, they make the 7-question version.
Question 4
If John can drink one barrel of water in 6 days, and Mary can drink one barrel of water in 12 days, how long would it take them to drink one barrel of water together?
Question 5
Jerry received both the 15th highest and the 15th lowest mark in the class. How many students are in the class?
Question 6
A man buys a pig for $60, sells it for $70, buys it back for $80, and sells it finally for $90. How much has he made?
Question 7
Simon decided to invest $8,000 in the stock market one day early in 2008. Six months after he invested, on July 17, the stocks he had purchased were down 50%. Fortunately for Simon, from July 17 to October 17, the stocks he had purchased went up 75%. At this point, Simon has: (a) broken even, (b) is ahead of where he began, or (c) has lost money?
Scoring yourself honestly is the hard part: it's very easy to "remember" that you got it right all along. IQ Tester does that step for you. It scores your answers for you, counts a skip as wrong, weights hard questions more, and shows which of its four categories (number series, verbal analogy, logic, pattern) you're strongest in. Find my weak spots
Answers and why your gut lied
Here are the cognitive reflection test answers, with the trap in each one.
| # | Gut answer | Correct answer | The trap |
|---|---|---|---|
| 1 | 10 cents | 5 cents | "$1.10 minus $1.00" feels done |
| 2 | 100 minutes | 5 minutes | Matching numbers, not rates |
| 3 | 24 days | 47 days | Halving time instead of thinking doubling |
| 4 | 9 days | 4 days | Averaging instead of adding rates |
| 5 | 30 | 29 | Counting Jerry twice |
| 6 | $10 | $20 | Treating it as one deal |
| 7 | (b) ahead | (c) lost money | Thinking +75% beats −50% |
Why each one works
- Bat and ball: If the ball is 10 cents, the bat is $1.10, and the total is $1.20. Too much. Ball = x, bat = x + 1.00, so 2x + 1.00 = 1.10, and x = 0.05. Ball is 5 cents, bat is $1.05.
- Widgets: Each machine makes one widget in 5 minutes. 100 machines make 100 widgets in the same 5 minutes.
- Lily pads: It doubles daily. If it's full on day 48, it was half full the day before: day 47.
- Barrel: John drinks 1/6 a day, Mary 1/12. Together that's 2/12 + 1/12 = 3/12 = 1/4 of a barrel per day. So 4 days.
- Jerry: 14 people above him, 14 below, plus Jerry. 14 + 14 + 1 = 29.
- Pig: First deal: +$10. Second deal: +$10. The $80 buy-back is a new purchase. Total: $20.
- Stocks: $8,000 down 50% is $4,000. Up 75% on $4,000 is +$3,000, so $7,000. He's down $1,000.
How people usually score
In Frederick's original 2005 paper, which tested thousands of people, most got at least one of the three questions wrong. Even at top universities like MIT, only around half got all three right.
A rough way to read your own cognitive reflection test score (this is a vibe check, not an official scale):
- 0-1 right: your fast brain is running the show. Totally normal.
- 2-3 right on the original / 4-5 on the 7: you're catching some traps.
- All 3 / 6-7 right: you pause and check. Or you've seen these on TikTok before (be honest).
Knowing the answers in advance ruins the test, which is exactly why the newer "alternative questions" exist. If you want more, many people search for a cognitive reflection test PDF, but the questions above are the standard ones.
Train slow thinking for exams
The CRT skill, catching your own first answer, shows up in every exam: SATs and ACTs in the US, GCSEs and A-levels in the UK, provincial exams in Canada.
How to think slow when it counts:
- Re-read the question once after answering. Especially the last line. What exactly is it asking for?
- Plug your answer back in. The bat-and-ball trap dies the moment you add 10 cents + $1.10.
- Watch for "feels too easy." On a test, an instant answer to a word problem is a red flag.
- Name the unit. Minutes? Days? Dollars per trip? Units expose rate traps like the widgets.
- Practice puzzles that punish gut answers. The Monty Hall problem and the viral 6÷2(1+2) are great reps.
Catch your gut before it costs you marks
Cognitive reflection test questions prove that fast isn't the same as right. If you fell for a few, you've found something worth training. IQ Tester's 20 untimed questions give you a free score band and three of your four category strengths in a few minutes, and its guides turn your weak spot (like logic, mental math or focus) into a short daily drill.
FAQ
What are the 3 cognitive reflection test questions?
The original three from Shane Frederick (2005) are the bat and ball problem (answer: 5 cents), the widget machines problem (5 minutes) and the lily pad problem (47 days). Each has a tempting wrong answer that pops up first.
What is the answer to the bat and ball problem?
The ball costs 5 cents and the bat costs $1.05. The popular answer of 10 cents is wrong because it would make the bat $1.10 and the total $1.20.
Is the cognitive reflection test an IQ test?
No. It uses simple math and measures whether you override your first, intuitive answer. It's related to reasoning, but it's a narrow test of one habit, not a full IQ measure.
Where can I take the cognitive reflection test online free?
You can try all seven cognitive reflection test questions on this page for free and check the answers above. Once you know the answers, retaking it doesn't tell you much, so try new puzzles instead.
What is a good score on the cognitive reflection test?
Getting all three original questions right is uncommon; most people miss at least one. On the 7-question version, 6 or 7 correct is strong, as long as you hadn't seen the questions before.