Important 81924

Karel went for a walk at a speed of 5 km/h. After 3 hours, Ondra rode to him with an important message. He was moving at a speed of 20 km/h. How many minutes did Ondra catch up with Karel?

Final Answer:

t =  60 min

Step-by-step explanation:

$$\begin{gathered} v_1=5\text{km/h} \\ {v}_2=20\text{km/h} \\ O=3\text{h} \\ {s}_1=s_2 \\ {v}_1\cdot (O+T)=v_2\cdot T \\ 5\cdot (3+T)=20\cdot T \\ 15T=15 \\ T=\frac{15}{15}=1 \\ T=1 \\ t=T\to \text{min}=T\cdot 60\text{min}=1\cdot 60\text{min}=60\text{min}=60\text{min} \end{gathered}$$

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