If X1is uniform on [0,1], and, conditional onX1,X2, is uniform on [0,X1]. Find the joint and marginal distributions of X1and X2.

The first one, i believe, would be correct. all the others have one thing in common, and that's that they have repeating numbers. in the second one, x and y have repeating 6's and 3's, and in the third, x and y have repeating 6's as well. in the last one, there are repeating 3's. the first one has no repeating numbers.

The correct answer is -20y