Volume of the cubical tank = 40 × 40 × 40 = 64&thinsp;000 cm&sup3; = 64 L.<br><br>
&bull; Water pumped out in 4 minutes = 4 × 4 = 16 L<br>
&bull; Water left = 64 − 16 = 48 L<br>
&bull; Percentage left = \(\frac{48}{64} \times 100\% = 75\%\)<br><br>
Final Answer: 75%