Research psychologist Interview Question:

Well, seriously, you might get asked brainteaser questions like these, especially in quantitative jobs. But remember that the interviewer doesn’t necessarily want an exact number—he wants to make sure that you understand what’s being asked of you, and that you can set into motion a systematic and logical way to respond. So, just take a deep breath, and start thinking through the math. (Yes, it’s OK to ask for a pen and paper!)