PSLE There was a total of 22758 cm
3 of water in rectangular tanks X and Y at first. The height of the water level in tank Y was 7 cm above that of tank X.
- Find the height of the water level in tank X.
- Penelope poured 4752 cm3 of water out of tank Y. Tank Y was then half filled with water. What was the height of tank Y?
(a)
Volume of water in Tank Y with a height of 7 cm
= 27 x 22 x 7
= 4158 cm
3 Volume of water in both tanks excluding the water that is 7 cm above that of Tank X
= 22758 - 4158
= 18600 cm
3 Base area of Tank X
= 21 x 16
= 336 cm
2 Base area of Tank Y
= 27 x 22
= 594 cm
2 Combined base areas of both tanks
= 336 + 594
= 930 cm
2 Height of water in Tank X
= 18600 ÷ 930
= 20 cm
(b)
Decrease in the height of Tank Y after some water was poured out
= 4752 ÷ 594
= 8 cm
Original height of water before some was poured out
= 20 + 7
= 27 cm
Height of water after some was poured out
= 27 - 8
= 19 cm
Height of Tank X
= 2 x 19
= 38 cm
Answer(s): (a) 20 cm; (b) 38 cm