PSLE There was a total of 23092 cm
3 of water in rectangular tanks C and D at first. The height of the water level in tank D was 5 cm above that of tank C.
- Find the height of the water level in tank C.
- Jen poured 7072 cm3 of water out of tank D. Tank D was then half filled with water. What was the height of tank D?
(a)
Volume of water in Tank D with a height of 5 cm
= 34 x 26 x 5
= 4420 cm
3 Volume of water in both tanks excluding the water that is 5 cm above that of Tank C
= 23092 - 4420
= 18672 cm
3 Base area of Tank C
= 28 x 24
= 672 cm
2 Base area of Tank D
= 34 x 26
= 884 cm
2 Combined base areas of both tanks
= 672 + 884
= 1556 cm
2 Height of water in Tank C
= 18672 ÷ 1556
= 12 cm
(b)
Decrease in the height of Tank D after some water was poured out
= 7072 ÷ 884
= 8 cm
Original height of water before some was poured out
= 12 + 5
= 17 cm
Height of water after some was poured out
= 17 - 8
= 9 cm
Height of Tank C
= 2 x 9
= 18 cm
Answer(s): (a) 12 cm; (b) 18 cm