PSLE
There was a total of 26583 cm³ of water in rectangular tanks R and S at first. The height of the water level in tank S was 3 cm above that of tank R.

1. Find the height of the water level in tank R.
2. Jean poured 5655 cm³ of water out of tank S. Tank S was then half filled with water. What was the height of tank S?

(a)
Volume of water in Tank S 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 R
= 26583 - 3393
= 23190 cm³

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

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

Combined base areas of both tanks
= 1188 + 1131
= 2319 cm²

Height of water in Tank R 
= 23190 ÷ 2319
= 10 cm

(b)
Decrease in the height of Tank S after some water was poured out 
= 5655 ÷ 1131
= 5 cm

Original height of water before some was poured out
= 10 + 3
= 13 cm

Height of water after some was poured out
= 13 - 5
= 8 cm

Height of Tank R
= 2 x 8
= 16 cm

Answer(s): (a) 10 cm; (b) 16 cm