A point (a, b) is distributed uniformly in the square
0<x<1, 0<y<1. Let S(a, b) be the area of a rectangle
with sides a and b. Find P{1/4 < S(a, b) < 1/3}
Break a stick of unit length at a uniformly chosen random point.
Then take the shorted of the two pieces and break it again in two
pieces at a uniformly chosen random point. Let X denote the
shortest of the final three pieces. Find the density of X.
Choose a point at random from the unit square [0, 1] × [0, 1].
We also choose the second random point, independent of the first,
uniformly on the line segment between (0, 0) and (1, 0). The random
variable A is the area of a triangle with its corners at (0, 0) and
the two selected points. Find the probability density function
(pdf) of A.
A point is chosen uniformly at random from a disk of radius 1,
centered at the origin. Let R be the distance of the point from the
origin, and Θ the angle, measured in radians, counterclockwise with
respect to the x-axis, of the line connecting the origin to the
point.
1. Find the joint distribution function of (R,Θ); i.e. find
F(r,θ) = P(R ≤ r, Θ ≤ θ).
2. Are R and Θ independent? Explain your answer.
Let X and Y be independent and uniformly distributed random
variables on [0, 1]. Find the cumulative distribution and
probability density function of Z = X + Y.
Let X and Y be uniformly distributed independent random
variables on [0, 1].
a) Compute the expected value E(XY ).
b) What is the probability density function fZ(z) of Z = XY
?
Hint: First compute the cumulative distribution function FZ(z) =
P(Z ≤ z) using a double integral, and then differentiate in z.
c) Use your answer to b) to compute E(Z). Compare it with your
answer to a).
1. Let X and Y be independent U[0, 1] random variables, so that
the point (X, Y) is uniformly distributed in the unit square.
Let T = X + Y.
(a) Find P( 2Y < X ).
(b). Find the CDF F(t) of T (for all real numbers t).
HINT: For any number t, F(t) = P ( X <= t) is just the area
of a part of the unit square.
(c). Find the density f(t).
REMARK: For a...
Let X and Y be random variables. Suppose P(X = 0, Y = 0) = .1,
P(X = 1, Y = 0) = .3, P(X = 2, Y = 0) = .2 P(X = 0, Y = 1) = .2,
P(X = 1, Y = 1) = .2, P(X = 2, Y = 1) = 0.
a. Determine E(X) and E(Y ).
b. Find Cov(X, Y )
c. Find Cov(2X + 3Y, Y ).
Pick an arbitrary consumption bundle (x, y) ∈ R2+ (meaning x ≥
0, y ≥ 0). Draw or describe the better than set (upper contour
set), the worse than set (lower contour set) and the indifference
set in a graph for the following situations:
• I like consuming x, and the more the better. I am completely
indifferent to the amount of y that I consume.
• As long as my consumption of x is less than x∗, the more...