The answers are here.Here’s a three-question “cognitive reflection test” devised by Massachusetts Institute of Technology researchers:
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 the lake?
BTW: This could be called a David Gordon test. If you talk to him over the phone or have a pastrami sandwich with him, he is going to throw something like the above at you. Though his tend to be more difficult, and even more so because nothing is written down and you have to bounce the elements around in your head without going back to paper to study them.