standard_description: Calculate the expected value of a random variable; interpret it as the mean of the probability distribution.
problem_activity: Rami leaves his house to drive to school. After driving west for
$$8\frac{3}{4}$$
miles, he realizes that he forgot his backpack at home.
How far and in what direction does Rami have to travel to get back to his house? Represent the situation on a number line, including labels for Rami’s house and school, and arrows to show his trips.


aligns: no