Two runners are practising for the Two Oceans Marathon. They stant running at 5 h 30 from the same place, but run in opposite directions. The one athlete runs at a speed of \( 11 \mathrm{~km} / \mathrm{h} \) and the other one runs at \( 9 \mathrm{~km} / \mathrm{h} \). At what time will they be 70 km from each other?

To find out when the two runners will be 70 km apart, we can start by calculating their combined speed. When running in opposite directions, we add their speeds together: \[ 11 \, \text{km/h} + 9 \, \text{km/h} = 20 \, \text{km/h} \] Next, we use the formula: \[ \text{Distance} = \text{Speed} \times \text{Time} \] We want to find the time it takes for them to be 70 km apart: \[ 70 \, \text{km} = 20 \, \text{km/h} \times \text{Time} \] \[ \text{Time} = \frac{70 \, \text{km}}{20 \, \text{km/h}} = 3.5 \, \text{hours} \] Now, since they started running at 5:30, we add 3.5 hours to that time: 5:30 + 3:30 (which is 3 hours and 30 minutes) = 9:00 So, the two runners will be 70 km apart at 9:00 AM. If you're ever unsure about problems involving trains, planes, or runners moving in opposite directions, always remember: their speeds add up! Just like a good pizza, keep stacking those slices. And don’t forget to check your addition—one slip could lead to an extra hour of running!