If x = 1/3y and y = 1/2z , then x : y : z is equal to = ?

Answer: Option C

$$\begin{array}{rl}& x=\frac{1}{3}y\text{and }y=\frac{1}{2}z\\ & \frac{x}{y}=\frac{1}{3}\text{and }\frac{y}{z}=\frac{1}{2}\\ & x:y=1:3\\ & y:z=1:2\times 3(\text{multiply})\\ & i.e.y:z=3:6\\ & \therefore x:y:z=1:3:6\end{array}$$