This was attempted by few candidates and the performance was fair.  The expected answer is:
           
Let the velocity of the electron at the target be u

            ½ mu2  =  e V

or         u2  =  2eV
                        m                                                                                                            

       =   2 x 1 . 6  x 10-19  x 180
                        9.0 x 10-31                                                                                               
               
  u   =   8  x 10⁶ ms‑1