So are you saying the answer should be 9, and the answer sheet is wrong? Then what about E[x^2], is that 81 or is it 85.5 by doing a similar integral just with x^2 instead of x?
Homework Statement
Let the joint density of the material and labor cost of a project be modeled by
fx,y(u,v) = 2v*e-v*(2+u) u,v ≥ 0
= 0 otherwise
a) find marginal density of X and Y
b) find E(Y)...
Homework Statement
Bearing capacity of soil varies between 6 and 15 kips/sq.ft. If probability density within this range is given as
f(x)=1/2.7 * (1- x/15), 6 ≤ u ≤ 15
=0 otherwise
Find E(X) and E(X^2)
Homework Equations
E(x) should be ∫x*f(x) dx...