Properties of the expected value - Exercise set 1

This exercise set contains some solved exercises on the properties of the expected value operator. The theory needed to solve these exercises is introduced in the lecture entitled Properties of the expected value.

Exercise 1.1

Let X and Y be two random variables, having expected values:[eq1]

Compute the expected value of the random variable Z defined as follows:[eq2]

nav_button Solution

Using the linearity of the expected value operator, we obtain:[eq3]

Exercise 1.2

Let X be a $2	imes 1$ random vector such that its two entries X_1 and X_2 have expected values:[eq4]

Let A be the following $2	imes 2$ matrix of constants:[eq5]

Compute the expected value of the random vector Y defined as follows:[eq6]

nav_button Solution

The linearity property of the expected value applies also to the multiplication of a constant matrix and a random vector:[eq7]

Exercise 1.3

Let Sigma be a $2	imes 2$ matrix with random entries, such that all its entries have expected value equal to 1. Let A be the following $1	imes 2 $ constant vector:[eq8]Compute the expected value of the random vector Y defined as follows:[eq9]

nav_button Solution

The linearity property of the expected value applies also to the multiplication of a constant vector and a matrix with random entries:[eq10]

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