Your level of confidence is a key to your success in many areas, especially investing. To test your confidence level, answer these ten questions. It will take only a few minutes to complete. For each question, provide a low and high guess such that you are 90% sure the correct answer falls between the two. Your challenge is to be neither too narrow (overconfident) nor too wide (underconfident). We'll tell you whether your score suggests you're too overconfident.