A machine prints out the number 1, 2, or 3 with equal probabilities. A machine
starts printing numbers independently one after another and stops the �rst time it prints 1. Let
X denote the number of 2s it printed. Compute E[X] and var(X).
starts printing numbers independently one after another and stops the �rst time it prints 1. Let
X denote the number of 2s it printed. Compute E[X] and var(X).