PSLE
There was a total of 26944 cm³ of water in rectangular tanks E and F at first. The height of the water level in tank F was 2 cm above that of tank E.

1. Find the height of the water level in tank E.
2. Ivory poured 4176 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 2 cm
= 36 x 29 x 2
= 2088 cm³

Volume of water in both tanks excluding the water that is 2 cm above that of Tank E
= 26944 - 2088
= 24856 cm³

Base area of Tank E
= 31 x 28
= 868 cm²

Base area of Tank F
= 36 x 29
= 1044 cm²

Combined base areas of both tanks
= 868 + 1044
= 1912 cm²

Height of water in Tank E 
= 24856 ÷ 1912
= 13 cm

(b)
Decrease in the height of Tank F after some water was poured out 
= 4176 ÷ 1044
= 4 cm

Original height of water before some was poured out
= 13 + 2
= 15 cm

Height of water after some was poured out
= 15 - 4
= 11 cm

Height of Tank E
= 2 x 11
= 22 cm

Answer(s): (a) 13 cm; (b) 22 cm