分步 aDerive the joint PDF fX(i),X(j)(x,y)f_{X_{(i)},X_{(j)}}(x,y)fX(i),X(j)(x,y) for 0<x<y<10 < x < y < 10<x<y<1.提交作答后加载提示与解析。
分步 bUsing the formula E[X(i)X(j)]=i(j+1)(n+1)(n+2)E[X_{(i)}X_{(j)}] = \frac{i(j+1)}{(n+1)(n+2)}E[X(i)X(j)]=(n+1)(n+2)i(j+1) for i<ji < ji<j, derive Cov(X(i),X(j))\operatorname{Cov}(X_{(i)}, X_{(j)})Cov(X(i),X(j)).提交作答后加载提示与解析。