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The Worlds Shortest IQ Test

    THE WORLD’S SHORTEST IQ TEST
    (THE COGNITIVE REFLECTION TEST)

    This Cognitive Reflection Test (CRT) was created by psychologist Shane Frederick in 2005. In a scientific paper published in The Journal of Economic Perspectives, Shane has picked these three questions for the CTR because they were all “found to yield impulsive erroneous responses.” The questions supposedly make it easy for people to quickly jump to conclusions instead of deeply analyzing the seemingly simple questions.

    Only 17% of students from the top universities in the world (like Yale and Harvard) got a perfect score on the CRT, according to a 2003 study.

    QUESTIONS

    The bat and the ball problem

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

    The Widget-Making Machine Problem

    If it takes 5 machines 5 minutes to make 5 widgets, how long would it take 100 machines to make 100 widgets?

    The Size-Double Lily Pad Patch Problem

    There is a patch of lily pads in a lake. 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 to cover half the lake?

    Scroll down to reveal the answers to these questions…

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    ANSWERS

    1. The ball costs 5 cents. (1.05 + 0.5 = 1.10)
    2. It would take 100 machines 5 minutes to make 100 widgets.
    3. The lily pads would cover half the lake in 47 days.