Not so quick that I need an answer RIGHT NOW because I'm still on the phone. Quick in the sense that the guy wanted an answer right away. I recently phone screened for a development job with a major software company, who told someone to call me up for the basic technical chat, which I assumed would be do you know what OOP is, can you code this algorithm, what specifically did you do for Project X, that kind of thing. It's the control gate for an on-site interview. Rather than speaking with a member of that group, I got a call from a research scientist only loosely affiliated with them. After some quick chit-chat, he asked me three questions: 1. Russian roulette. Given a revolver with 6 chambers and bullets in 2. The bullets are in consecutive chambers. If your opponent pulls the trigger and dry-fires (no bullet), which is more advantageous to you on your turn: just pulling the trigger, or spinning the cylinder and then pulling the trigger? 2. How many dice do you need to roll at once to produce a 95% chance of rolling at least one six? 3. Given the following sample: 100 boys with an average of 10 absences a year and a standard deviation of 7 50 girls with an average of 10 absences a year and a standard deviation of 6 What is the probability of a random boy having at most 3 more days of absence than a random girl? The first one was interesting once I regarded it as a state space rather than basic probability. As handed to me, the gun would have the hammer on an empty chamber and 2/5 remaining chambers loaded, meaning a 40% chance of drawing a bullet. If I spin, I reset this back to 2/6 loaded, or roughly 33%. Spinning is the better move. With the rounds being loaded next to each other, this changes. With the hammer on an empty chamber, I have five possible state transitions: beginning of the loaded sequence (1) or beginning of an empty sequence (3). Thus I have a 25% chance of shooting myself, meaning it's better to just pull the trigger. The second question is basic- 16.7% chance of rolling a 6 with one die. Need to get to 95% by adding dice, so 95/16.7 is 6.58 dice, round up to 6 dice. The third question derailed me. I looked at it as a Gaussian overlap problem; the two distributions have overlapping tails with an associated probability. They're both within 1 standard deviation of each other. The "at most" is what knocked me off track. I understand the idea here, but I wasn't sure how to approach it. How would I go about solving this? This was all pencil & paper over the phone stuff- no calculators, Google, what have you. Side question- is this a useful phone screen? What does the fact that I didn't solve the third question say about my ability to write code in my specific domain, or in general? WHY ARE MY LINE BREAKS DISAPPEARING?