PSLE
There was a total of 13186 cm³ of water in rectangular tanks R and S at first. The height of the water level in tank S was 2 cm above that of tank R.

1. Find the height of the water level in tank R.
2. Anna poured 2204 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 2 cm
= 29 x 19 x 2
= 1102 cm³

Volume of water in both tanks excluding the water that is 2 cm above that of Tank R
= 13186 - 1102
= 12084 cm³

Base area of Tank R
= 24 x 19
= 456 cm²

Base area of Tank S
= 29 x 19
= 551 cm²

Combined base areas of both tanks
= 456 + 551
= 1007 cm²

Height of water in Tank R 
= 12084 ÷ 1007
= 12 cm

(b)
Decrease in the height of Tank S after some water was poured out 
= 2204 ÷ 551
= 4 cm

Original height of water before some was poured out
= 12 + 2
= 14 cm

Height of water after some was poured out
= 14 - 4
= 10 cm

Height of Tank R
= 2 x 10
= 20 cm

Answer(s): (a) 12 cm; (b) 20 cm