PSLE
There was a total of 33894 cm³ of water in rectangular tanks E and F at first. The height of the water level in tank F was 5 cm above that of tank E.

1. Find the height of the water level in tank E.
2. Pamela poured 7714 cm³ of water out of tank F. Tank F was then half filled with water. What was the height of tank F?

(a)
Volume of water in Tank F with a height of 5 cm
= 38 x 29 x 5
= 5510 cm³

Volume of water in both tanks excluding the water that is 5 cm above that of Tank E
= 33894 - 5510
= 28384 cm³

Base area of Tank E
= 28 x 24
= 672 cm²

Base area of Tank F
= 38 x 29
= 1102 cm²

Combined base areas of both tanks
= 672 + 1102
= 1774 cm²

Height of water in Tank E 
= 28384 ÷ 1774
= 16 cm

(b)
Decrease in the height of Tank F after some water was poured out 
= 7714 ÷ 1102
= 7 cm

Original height of water before some was poured out
= 16 + 5
= 21 cm

Height of water after some was poured out
= 21 - 7
= 14 cm

Height of Tank E
= 2 x 14
= 28 cm

Answer(s): (a) 16 cm; (b) 28 cm