PSLE
There was a total of 23834 cm³ of water in rectangular tanks Q and R at first. The height of the water level in tank R was 4 cm above that of tank Q.

1. Find the height of the water level in tank Q.
2. Nicole poured 6216 cm³ of water out of tank R. Tank R was then half filled with water. What was the height of tank R?

(a)
Volume of water in Tank R with a height of 4 cm
= 37 x 28 x 4
= 4144 cm³

Volume of water in both tanks excluding the water that is 4 cm above that of Tank Q
= 23834 - 4144
= 19690 cm³

Base area of Tank Q
= 29 x 26
= 754 cm²

Base area of Tank R
= 37 x 28
= 1036 cm²

Combined base areas of both tanks
= 754 + 1036
= 1790 cm²

Height of water in Tank Q 
= 19690 ÷ 1790
= 11 cm

(b)
Decrease in the height of Tank R after some water was poured out 
= 6216 ÷ 1036
= 6 cm

Original height of water before some was poured out
= 11 + 4
= 15 cm

Height of water after some was poured out
= 15 - 6
= 9 cm

Height of Tank Q
= 2 x 9
= 18 cm

Answer(s): (a) 11 cm; (b) 18 cm