Two liquids $X$ and $Y$ form an ideal solution. At 300 K, vapour pressure of the solution containing 1 mol of $X$ and 3 mol of $Y$ is 550 mmHg. At the same temperature, if 1 mol of $Y$ is further added to this solution, vapour pressure of the solution increases by 10 mmHg. Vapour pressure (in mmHg) of $X$ and $Y$ in their pure states will be, respectively:\\
(1) 200 and 300\\
(2) 300 and 400\\
(3) 400 and 600\\
(4) 500 and 600