Given,
Mass of the bumper car is 150 kg.
It moves with a speed 10 m//s.
The mass of the stationary bumper car is 200 kg.
After collision,
The 200 kg bumper moves it a velocity of 8.0 m/s.
By conservation of mass,
[tex]\begin{gathered} 150\times10=200\times8+150v \\ \Rightarrow v=-0.66\text{ m/s} \end{gathered}[/tex]Thus the 150 kg bumper car moves backward after collision.