Answer :
[tex]\begin{gathered} \text{speed}\Rightarrow234000\text{ m/min} \\ \Rightarrow\frac{234000m}{\min}\times\frac{1\text{ km}}{1000\text{m}}\times\frac{\min }{60\text{ sec}} \\ \Rightarrow3.9\text{ km/s} \end{gathered}[/tex]