$0**9$ Itw $In1km$ races, runner $1$ on track $1($with time $2$ min, $27\mathrm{.}95$ s $)$ appears to be faster than runner $2$ on track $2(2$min,$28\mathrm{.}15s).$ However, length $L_2$ of track $2$ might be slightly greater than length $L_1$ of track $1.$ How large can $L_2-L_1$ be for us still to conclude that runner $1$ is faster?