April 5

Homework:

• Recall, that if you have 9 lookalike coins, one of which is fake (heavier), you can find it  with just 2 weighing on the scale (remember how?).
  Can you do the same with 10 coins? Can you find the fake coin among 10 coins with 3 weighings? among 11 coins with 3 weighings? 20? 25? How?


• If you lost you friend in Paris (and neither of you have a cell phone!), how you would look for her?


• If you have  vectors A(1,2), B(-2,1) and C(1,-3), what is A+B+C? (Recall, that you have to walk these three vectors one after another, starting at (0,0)).