Newspapers 5601

Four deliver newspapers. One takes 60 minutes, the second 40 minutes, the third 120 minutes, and the fourth 80 minutes. If they left at the same time, at 8 o'clock, when will they meet again at the place they left?

Result

t = 12:00 hh:mm

Step-by-step explanation:

$$\begin{gathered} 60=2^2\cdot 3\cdot 5 \\ 40=2^3\cdot 5 \\ 120=2^3\cdot 3\cdot 5 \\ 80=2^4\cdot 5 \\ LCM(60,40,120,80)=2^4\cdot 3\cdot 5=240 \\ t=8.00+LCM(60,40,120,80)/60=12=12:00\text{hh}:\text{mm} \end{gathered}$$

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