In a Wheatstone bridge (see fig.), Resistances $P$ and $Q$ are approximately equal. When $R = 400 \Omega$, the bridge is balanced. On interchanging P and Q, the value of R, for balance, is $405 \Omega$. The value of $Y$ is close to\\
(1) 401.5 ohm\\
(2) 404.5 ohm\\
(3) 403.5 ohm\\
(4) 402.5 ohm