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World's Shortest IQ Test Only Has Three Questions But 80 Percent Of People Fail It

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World's Shortest IQ Test Only Has Three Questions But 80 Percent Of People Fail It

Do you fancy yourself as being someone with a high IQ? Maybe you're interested in finding out whether you're smart but when it comes to sitting a test realise you don't have the time, patience or energy?

Well, this is where the world's shortest IQ test comes in really handy because it shouldn't take too long to get some answers.

It's not a new test and has been around since a 2005 research paper was published by professor Shane Frederick but it resurfaces online every now and then, with more and more people giving it a crack.

Credit: Alamy
Credit: Alamy

Prof Frederick has 3,000 participants complete the test and only 17 percent managed to get full marks and score 3/3. Impressive.

So... what're we waiting for? Here are the questions:

1. A bat and a ball cost $1.10 in total. The bat costs $1 more than the ball. How much does the ball cost?

2. If it takes five machines five minutes to make five widgets, how long would it take 100 machines to make 100 widgets?


3. 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 of the lake?

Got a headache yet? That's not an IQ question.

Credit: Wiki Commons
Credit: Wiki Commons

People usually give the answers (in order of the above questions) as 10 cents, 100 minutes and 24 days.


Explaining why the former is incorrect, prof Frederick said: "Anyone who reflects upon it for even a moment would recognise that the difference between $1 and 10 cents is only 90 cents, not $1 as the problem stipulates.

"In this case, catching that error is tantamount to solving the problem, since nearly everyone who does not respond '10 cents' does, in fact give the correct response."

What're the answers then? *Drumroll, please*: 5 cents, 5 minutes and 47 days.

Credit: Alamy
Credit: Alamy

If your head is still banging, don't worry. Presh Talwalkar explained the answers on his blog, Mind Your Decisions.

Outlining the first question, he wrote: "Say the ball costs X. Then the bat costs $1 more, so it is X + 1. So we have bat + ball = X + (X + 1) = 1.1 because together they cost $1.10. This means 2X + 1 = 1.1, then 2X = 0.1, so X = 0.05. This means the ball costs 5 cents and the bat costs $1.05."

When it comes to puzzle number two, he went on: "If it takes 5 machines 5 minutes to make 5 widgets, then it takes 1 machine 5 minutes to make 1 widget (each machine is making a widget in 5 minutes). If we have 100 machines working together, then each can make a widget in 5 minutes. So there will be 100 widgets in 5 minutes."

And for the final riddle, he said: "Every day FORWARD the patch doubles in size. So every day BACKWARDS means the patch halves in size. So on day 47 the lake is half full."


Aaaaand, I'm going for a lie down - safe in the knowledge that I'm not as smart as this 11-year-old, who scored the highest Mensa mark ever.


Featured Image Credit: Alamy

Topics: Viral

Rebecca Shepherd
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