X is a cubical tank of sides 20 cm and Y is a rectangular tank. The base of Y has dimensions as shown. X was fully filled with water and Y was empty. Samuel poured some water from X into Y without spilling. After that, the heights of the water level of X and Y were the same. What was the final height of the water level in both tanks? Answer : ___

1. Calculate the total volume of water in tank X initially

Volume of water = $20 \times 20 \times 20 = 8000 \text{ cm}^3$

2. Calculate the combined base area of tanks X and Y

Base area of X = $20 \times 20 = 400 \text{ cm}^2$
Base area of Y = $60 \times 20 = 1200 \text{ cm}^2$
Total base area = $400 + 1200 = 1600 \text{ cm}^2$

3. Calculate the final common height of the water level

Final height = $\frac{\text{Total volume}}{\text{Total base area}} = \frac{8000}{1600} = 5 \text{ cm}$