PSLE
There was a total of 20097 cm³ of water in rectangular tanks W and X at first. The height of the water level in tank X was 3 cm above that of tank W.

1. Find the height of the water level in tank W.
2. Victoria poured 3255 cm³ of water out of tank X. Tank X was then half filled with water. What was the height of tank X?

(a)
Volume of water in Tank X with a height of 3 cm
= 31 x 21 x 3
= 1953 cm³

Volume of water in both tanks excluding the water that is 3 cm above that of Tank W
= 20097 - 1953
= 18144 cm³

Base area of Tank W
= 21 x 17
= 357 cm²

Base area of Tank X
= 31 x 21
= 651 cm²

Combined base areas of both tanks
= 357 + 651
= 1008 cm²

Height of water in Tank W 
= 18144 ÷ 1008
= 18 cm

(b)
Decrease in the height of Tank X after some water was poured out 
= 3255 ÷ 651
= 5 cm

Original height of water before some was poured out
= 18 + 3
= 21 cm

Height of water after some was poured out
= 21 - 5
= 16 cm

Height of Tank W
= 2 x 16
= 32 cm

Answer(s): (a) 18 cm; (b) 32 cm