Sample Question #31 (probability theory)
There are 30 people in my group. What are the odds that at least two people share the same birth month and day (e.g., July 25). What are the odds that exactly two people share the same birth month and day? Finally, what are the odds that everybody was born in the same decade (where a decade is defined as any ten-year span, not necessarily "50s" or "60s" or "70s" etc.)?
(Comment: probability-related questions are very common in Wall Street interviews)