A gambler has the following strategy when playing the roulette:
* she bets 1 dollar on red and if she wins she stops,
* if she loses, she bets 2 dollars on red and then stops.
The roulette has 38 numbers from which 0 and 00 are green and the rest are red or black. When a gambler bets on red, the gambler wins if the ball stops at any of the red numbers. In addition, the payout when betting on colors is 1:1 (i.e. if one wins, one gets back double the money one bet).
a) Find the probability she loses 3 dollars.
b) Find the probability she won on the first bet given that she made 1 dollar.
c) If X is the amount of money she won, find E[X].
d) Suppose the gambler changes her strategy and now bets 1 dollar every time on red and never stops. So, on every bet she either wins or loses a dollar. Find the expected number of bets she will make till she wins at least 3 out of 4 consecutive bets.