Odpowiedź:
V₁ = 60 km / h
V₂ = 40 km / h
[tex]V_{sr} = \frac{V_{1} * t_{1} + V_{2} * t_{2}}{t_{1}+t_{2}}[/tex]
[tex]V_{1} = \frac{S}{t_{1}}[/tex]
[tex]V_{2} = \frac{S}{t_{2}}[/tex]
[tex]t_{1} = \frac{S}{V_{1}}[/tex]
[tex]t_{2} = \frac{S}{V_{2}}[/tex]
[tex]t_{1} = \frac{S}{60}[/tex]
[tex]t_{2} = \frac{S}{40}[/tex]
[tex]V_{sr} = \frac{60*\frac{S}{60}+40*\frac{S}{40}}{\frac{S}{60}+\frac{S}{40}} = \frac{2S}{\frac{2S}{120}+\frac{3S}{120}} = 2S * \frac{120}{5S} = \frac{240S}{5S} = 48\ km / h[/tex]