2. Suppose X and Y are the survival times (in days) of two white rats that were subjected to different levels of radiation. Assume that X and Y are independent, fX(x)={(1+x)21,0,x>0 elsewhere.fY(y)={(1+y)32,0,y>0elsewhere. Show all your work and circle your final answers. Correct answers with no justifications will not receive any marks. a) Give the joint density of X and Y. b) Find the probability that the second rat outlives the first rat, P[X<Y]..