A $280 \;V$, separately excited $\text{DC}$ motor with armature resistance of $1\:\Omega$ and constant field excitation drives a load. The load torque is proportional to the speed. The motor draws a current of $30 A$ when running at a speed of $1000$ $\text{rpm}$. Neglect frictional losses in the motor. The speed, in rpm, at which the motor will run, if an additional resistance of value $10\:\Omega$ is connected in series with the armature, is _____________. (round off to nearest integer)