(i) The value of $x + y + z$ is 15 . If $a,x,y,z,b$ are in A.P. while the value of $\frac{1}{x} + \frac{1}{y} + \frac{1}{z}$ is $\frac{5}{3}$. If $a,x,y,z,b$ are in H.P. then find $a$ and $b$. (ii) If $x,y,z$ are in H.P. then show that $log(x + z) + log(x + z - 2y) = 2log(x - z)$.