Find total volume, divide by 50, then divide by the small base area.<br><br>
&bull; Total water = 40 × 25 × 9 = 9000 cm&sup3;<br>
&bull; Each small cuboid gets = 9000 ÷ 50 = 180 cm&sup3;<br>
&bull; Base area of each small = 10 × 6 = 60 cm&sup2;<br>
&bull; Height in each = 180 ÷ 60 = 3 cm<br><br>
Final Answer: 3 cm