I wonder if "How smart are you?" tests really tests the smartness of people. But it's quite hard to answer all the questions correct, hard may not be the right word. How about time consuming? I would read a question, answer right away, check the answer, find my answer incorrect, smile and would ask myself, "Am I really dumb?" It's just a mind trick. We would just let our sub-conscious mind work on it; many of our answers would just come instantly like 2+2=4. Try it yourself.