What is the Expected Value of the grades?What is the variance of the grades?

Econ203
Assignment 9
1. Table below summarizes the distribution of grades in Schools.
a. What is the Expected Value of the grades?
b. What is the variance of the grades?
Grades Probability
99 0.45
95 0.25
75 0.1
55 0.10
5 0.10
You should provide both the calculation and the formulas.
c. With the same variable provided in the table for q1, provide both a distribution as well as the Cumulative probability
distribution. .
2. Table below summarizes the result of a survey over all Target stores in the US, and it provides the number of customers arriving at the checkout point in Target stores, as well as the probability of each number:
a. What is the average of the number of customers arriving at the checkout point?
b. What is the variance?
c. Provide the distribution and cumulative distribution .
3. In the 2 data sets below find the expected value.
Then just think about while the mean is the same why the range of x and variation in the numbers x can take is so different in the 2 J . You do
not need to calculate variance.
x P(x)
1 0.1
2 0.3
3 0.45
4 0.15
y P(y)
-1000 0.38675
-100 0.1
100 0.1265
1000 0.38675
4. What is an example of discrete variable and a continuous variable

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