Chapter 2 - Describing Motion: Kinematics in One Dimension - Problems - Page 44: 35

6.3s

You first find the initial velocity that the runner is at: $V_0$ = (10000-1200)/(27 *60) = 5.43 Then, you know that he has to complete 1200m in 180s so he has to reach a final speed ($V_f$) of 6.7 $m/s$. So by using the given acceleration 0.2 $m$/$s^2$ and the formula $V_f$ = $V_0$ + $at$: $t$ = ($V_f$ - $V_0$)/ $a$ $= (6.7 - 5.43) / 0.2 = 6.3$s