b) Compute the first and second derivative of the cumulant generating function. O K'x (t ) = 1 1 1 - Bt and Kx (t ) = (1 - Bt)2 O B 82 Kx (t ) = : 1 - Bt and Kx (t) = (1 - Bt)2 O B K'x(t) = B 1 - Bt and Kx (t ) = (1 - Bt)2 O K'x(t) = 1 - 3t and (1 - Bt) B Ky(t) = 82 O 1 - 3t K'y (t) = and B K* (t) = (1 - Bt)2 BE) Hence, or otherwise determine the approximate density for Y : 211:1 X5 : n2. Hint: consider applying the density transformation formula and use the approximation 11\