

2. [10 marks] Let Xı ~ Gamma(k, 1), X2X1 = li ~ Gamma(m, x1). (a) [5...
15 marksLet Xi ~ Gamma(k, λ), (a) 5 marks] Show that X2 has a PDF given by 0. (b) [5 marks] Use the conditional mean and variance fornulae given in Theorem 2.40 to find E(X2 and Var(X2), for k> 2. (This means don't derive them directly from the PDF given in part (a). (c) [5 marks] Show that XIX,-x2 ~ Gamma(k +1, λ +12).
Let X1 and X2 be independent gamma distribution random variables with gamma (a1,1) and gamma (a2, 1). Find the marginal distributions of x1/(x1+x2) and x2/(x1+x2).
iid 14 marksAssume that e Denote T 4i Gamma(k, A) and X1,... , X,,e Poisson(0) (a) [4 marks Show that the posterior distribution of 0 is Gamma(nTk, n ). (b) [4 marks Find the probability function of the marginal distribution of Y = nX. (Note that the conditional distribution of on Y is not the same X1, ..., Xn.) as on
iid 14 marksAssume that e Denote T 4i Gamma(k, A) and X1,... , X,,e Poisson(0) (a) [4 marks Show...
1. Let X1 and X2 have the joint pdf f(x1, x2) = 2e-11-22, 0 < 11 < 1 2 < 0o, zero elsewhere. Find the joint pdf of Yı = 2X1 and Y2 = X2 – Xı.
2. Let X1, .., X6 be i.i.d from Pois() with 2 with pdf 20. Suppose A has the prior Gamma(a,B) _ Aa-1e-1в Г(а) т(A) - where a 10, 3 = 4 (i) Find the Bayes Estimate of A (ii) Find a 90% credible interval for A (Use the x2 table and equal tail areas)
2. Let X1, .., X6 be i.i.d from Pois() with 2 with pdf 20. Suppose A has the prior Gamma(a,B) _ Aa-1e-1в Г(а) т(A) - where...
Let X1, . . . , Xn be a sample taken from the Gamma distribution Γ(2, θ−1) with pdf f(x,θ)= θ^2xexp(−θx) if x ≥ 0, θ ∈ (0,∞), and 0 otherwise, (A) Show that Y = ∑ni=1 Xi is a complete and sufficient statistic. (B) Find E(1/Y) . Hint: If W ∼ χ2(k) then E(W^m) = 2mΓ(k/2+m) for m > −k/2. Note also that Y Γ(k/2) Γ(n) = (n − 1)!, n ∈ N∗ . Facts from 1(C) are useful:...
Let (X1,X2,X3) have the joint pdf fx(x1, x2, x3) = k*x1*x2*x3; 0 < x1 < x2 < x3 < 1. Consider the transformation U1 = X1/X2; U2 = X2/X3; U3 = X3. a) Find the value of k. b) Find the joint pdf fu(u1, u2, u3) of U1,U2,U3.
5. Let X; (i = 1, 2, 3) be be independent gamma random variables with a; = i and B. = 8. a. Find a maximum likelihood estimator of 8 and prove that it is unbiased. b. Show that 2(X1+X2+Xa) is a pivotal quantity for 0. c. Find a 95% confidence interval for 6.
Exercise 7 (team 5) Let Xi and X2 have joint pdf x1 + x2 if0<x1 < 1 and 0 < x2 < 1 /h.x2 (x1,x2) = 0 otherwise. When Y1 X1X2 derive the marginal pdf for Y.
Let X1 and X2 have the joint pdf as fX1,X2 (x1, x2) = e −(x1+x2) , 0 < x1 < ∞, 0 < x2 < ∞. Find the pdf of X1 + X2 through the following two-step procedure. (a) Find the joint pdf of Y = X1 + X2 and Z = X2, and specify the domain. (b) Find the marginal pdf of Y = X1 + X2.