PSLE There was a total of 15280 cm
3 of water in rectangular tanks M and N at first. The height of the water level in tank N was 5 cm above that of tank M.
- Find the height of the water level in tank M.
- Wendy poured 3360 cm3 of water out of tank N. Tank N was then half filled with water. What was the height of tank N?
(a)
Volume of water in Tank N with a height of 5 cm
= 28 x 20 x 5
= 2800 cm
3 Volume of water in both tanks excluding the water that is 5 cm above that of Tank M
= 15280 - 2800
= 12480 cm
3 Base area of Tank M
= 24 x 20
= 480 cm
2 Base area of Tank N
= 28 x 20
= 560 cm
2 Combined base areas of both tanks
= 480 + 560
= 1040 cm
2 Height of water in Tank M
= 12480 ÷ 1040
= 12 cm
(b)
Decrease in the height of Tank N after some water was poured out
= 3360 ÷ 560
= 6 cm
Original height of water before some was poured out
= 12 + 5
= 17 cm
Height of water after some was poured out
= 17 - 6
= 11 cm
Height of Tank M
= 2 x 11
= 22 cm
Answer(s): (a) 12 cm; (b) 22 cm