PSLE
There was a total of 44766 cm³ of water in rectangular tanks K and L at first. The height of the water level in tank L was 4 cm above that of tank K.

1. Find the height of the water level in tank K.
2. Barbara poured 7020 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 4 cm
= 39 x 30 x 4
= 4680 cm³

Volume of water in both tanks excluding the water that is 4 cm above that of Tank K
= 44766 - 4680
= 40086 cm³

Base area of Tank K
= 36 x 33
= 1188 cm²

Base area of Tank L
= 39 x 30
= 1170 cm²

Combined base areas of both tanks
= 1188 + 1170
= 2358 cm²

Height of water in Tank K 
= 40086 ÷ 2358
= 17 cm

(b)
Decrease in the height of Tank L after some water was poured out 
= 7020 ÷ 1170
= 6 cm

Original height of water before some was poured out
= 17 + 4
= 21 cm

Height of water after some was poured out
= 21 - 6
= 15 cm

Height of Tank K
= 2 x 15
= 30 cm

Answer(s): (a) 17 cm; (b) 30 cm