The first

The first 300 km of a journey is covered in 10/3 hours, and the remaining journey is covered in 8/3 hours at 75 km/h. Find the average speed of the whole journey.

Final Answer:

v =  83.3333 km/h

Step-by-step explanation:

$$\begin{gathered} s_1=300\text{km} \\ {t}_1=10/3=\frac{10}{3}\doteq 3.3333\text{h} \\ {t}_2=8/3=\frac{8}{3}\doteq 2.6667\text{h} \\ {v}_2=75\text{km/h} \\ {s}_2=v_2\cdot t_2=75\cdot 2.6667=200\text{km} \\ s=s_1+s_2=300+200=500\text{km} \\ t=t_1+t_2=3.3333+2.6667=6\text{h} \\ v=s/t=500/6=83.3333\text{km/h} \end{gathered}$$

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