90% of the tank's capacity is 5400 cm&sup3;.<br><br>
&bull; 90% → \(\frac{9}{10}\) of capacity = 5400<br>
&bull; 10% → 5400 ÷ 9 = 600<br>
&bull; 100% → 600 × 10 = 6000<br><br>
Final Answer: 6000 cm&sup3;