Full volume of the tank = 60 × 60 × 40 = 144&thinsp;000 cm&sup3; = 144 L.<br><br>
&bull; The tank is half filled, so 144 ÷ 2 = 72 L of water are already in it.<br>
&bull; Remaining volume to fill = 72 L<br>
&bull; Time needed = 72 ÷ 6 = 12 minutes<br><br>
Final Answer: 12 minutes