PSLE
There was a total of 13980 cm³ of water in rectangular tanks K and L at first. The height of the water level in tank L was 2 cm above that of tank K.

1. Find the height of the water level in tank K.
2. Vanessa poured 2700 cm³ of water out of tank L. Tank L was then half filled with water. What was the height of tank L?

(a)
Volume of water in Tank L with a height of 2 cm
= 25 x 18 x 2
= 900 cm³

Volume of water in both tanks excluding the water that is 2 cm above that of Tank K
= 13980 - 900
= 13080 cm³

Base area of Tank K
= 17 x 12
= 204 cm²

Base area of Tank L
= 25 x 18
= 450 cm²

Combined base areas of both tanks
= 204 + 450
= 654 cm²

Height of water in Tank K 
= 13080 ÷ 654
= 20 cm

(b)
Decrease in the height of Tank L after some water was poured out 
= 2700 ÷ 450
= 6 cm

Original height of water before some was poured out
= 20 + 2
= 22 cm

Height of water after some was poured out
= 22 - 6
= 16 cm

Height of Tank K
= 2 x 16
= 32 cm

Answer(s): (a) 20 cm; (b) 32 cm