Playground 25761

Vašek is supposed to be on the playground, which is 2.5 km away from his home, in 15 hours and 30 minutes. What time does he have to ride his bike to be on the field 5 minutes earlier if he drives at 50km/h?

Result

t = 15:22 hh:mm

Step-by-step explanation:

$$\begin{gathered} t_1=15+30/60=\frac{31}{2}=15.5\text{h} \\ {t}_2=\frac{5}{60}=\frac{1}{12}\doteq 0.0833\text{h} \\ s=2.5\text{km} \\ v=50\text{km/h} \\ {t}_3=s/v=2.5/50=\frac{1}{20}=0.05\text{h} \\ t=t_1-t_2-t_3=\frac{31}{2}-\frac{1}{12}-\frac{1}{20}=\frac{930}{60}-\frac{5}{60}-\frac{3}{60}=\frac{930-5-3}{60}=\frac{922}{60}=15.36667=15:22\text{hh}:\text{mm} \end{gathered}$$

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