PSLE There was a total of 14616 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.
- Linda poured 4320 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 20 x 7
= 3780 cm
3 Volume of water in both tanks excluding the water that is 7 cm above that of Tank X
= 14616 - 3780
= 10836 cm
3 Base area of Tank X
= 18 x 13
= 234 cm
2 Base area of Tank Y
= 27 x 20
= 540 cm
2 Combined base areas of both tanks
= 234 + 540
= 774 cm
2 Height of water in Tank X
= 10836 ÷ 774
= 14 cm
(b)
Decrease in the height of Tank Y after some water was poured out
= 4320 ÷ 540
= 8 cm
Original height of water before some was poured out
= 14 + 7
= 21 cm
Height of water after some was poured out
= 21 - 8
= 13 cm
Height of Tank X
= 2 x 13
= 26 cm
Answer(s): (a) 14 cm; (b) 26 cm