高频题（0）
1. Experiement design
Feed ranking algorithm change, 怎么设计ab test
2. Define function
f(x) = a*x**2 + b*x + c, 给一个sorted list，用发f(x) generate一个sorted output。
3. Dice questions
M-sided dice, prob list, generate output
4. Simpson paradox
两种email version，连续两周在两个不同的城市做实验，显示结果是B好于A。combine起来是A好。
5. Predictive model
1 million rows, 10 K feature, someone was hired or not for a position. Predict the likelihood of a user being hired for a position.
