PSLE
There was a total of 35377 cm³ of water in rectangular tanks T and U at first. The height of the water level in tank U was 3 cm above that of tank T.

1. Find the height of the water level in tank T.
2. Risa poured 4524 cm³ of water out of tank U. Tank U was then half filled with water. What was the height of tank U?

(a)
Volume of water in Tank U with a height of 3 cm
= 39 x 29 x 3
= 3393 cm³

Volume of water in both tanks excluding the water that is 3 cm above that of Tank T
= 35377 - 3393
= 31984 cm³

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

Base area of Tank U
= 39 x 29
= 1131 cm²

Combined base areas of both tanks
= 868 + 1131
= 1999 cm²

Height of water in Tank T 
= 31984 ÷ 1999
= 16 cm

(b)
Decrease in the height of Tank U after some water was poured out 
= 4524 ÷ 1131
= 4 cm

Original height of water before some was poured out
= 16 + 3
= 19 cm

Height of water after some was poured out
= 19 - 4
= 15 cm

Height of Tank T
= 2 x 15
= 30 cm

Answer(s): (a) 16 cm; (b) 30 cm