Jump Trading Interview Questions

Compute the expected value of the maximum of n dice rolls.

There are four balls, two black and two white. You randomly pick two balls and flip their color (black to white or white to black). You repeat this process. How many times, on average, must you repeat this to ensure all four balls are the same color?

There are four balls: two black and two white. You randomly pick two balls and flip their colors (from black to white or vice versa), and repeat this process. How many times must you repeat this process to be certain that all four balls end up the same color?