# CS 70 Reading Quiz -- Week 12, Sunday

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1. I roll two fair 6-sided dice. Let the random variable X denote the sum of the two numbers that come up. What is the probability that X=11?

2. Consider the following gambling game (a simplified version of craps). You roll two fair 6-sided dice, and let X = the sum of the two numbers that come up. If X=7 or X=11, you win \$1. If X=2, X=3, or X=12, you lose \$1. Otherwise, you win nothing -- it's a wash. Let the random variable W denote the number of dollars you win (W is positive if you win some money, or negative if you lose money). Compute Pr[W=1]. (Show how you got it.)

3. Let W be as defined in question 2. Compute E[W]. (Show how you got it.)

4. What did you find difficult or confusing about the reading or the lectures, and what would you most like to see explained better? If nothing was difficult or confusing, and you understand the material pretty well, tell us what you found most interesting. Please be as specific as possible.