A tortoise and a hare race

First of all to facilitate our calculations, we should know both the hare's and tortoise's speed in terms of m/sec and that can be done as follows: hare's speed= $36 \times 1000/60^2 =10 m/sec$ tortoise's speed= $0.5 \times 1000/60^2 = \frac{5} {36} m/sec$ Now, by multiplying the hare's speed to the time it took to move, we'll deduce that it moved 100 metres. To know how long the tortoise took in order to move this distance, you'll divide the distance $100m$ by the tortoise's speed $\frac{5}{36} m/sec$ and we'll deduce that it'll take 720 seconds to catch up with the hare, which equals $\boxed{12 }$ minutes.