Runner

Peter ran at a speed of 12.4 km/h. After 45 minutes of running, he had a hiatus. The track is 31 km long. How many kilometers is he still to run if he still runs at the same speed?

Correct answer:

x =  21.7 km

Step-by-step explanation:

$$\begin{gathered} v=12.4\text{km/h} \\ t=45\text{min}\to \text{h}=45:60\text{h}=0.75\text{h} \\ s=v\cdot t=12.4\cdot 0.75=\frac{93}{10}=9.3\text{km} \\ {s}_0=31\text{km} \\ x=s_0-s=31-9.3=21.7\text{km} \end{gathered}$$

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