PSLE There was a total of 14728 cm
3 of water in rectangular tanks M and N at first. The height of the water level in tank N was 7 cm above that of tank M.
- Find the height of the water level in tank M.
- Min poured 4928 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 7 cm
= 28 x 22 x 7
= 4312 cm
3 Volume of water in both tanks excluding the water that is 7 cm above that of Tank M
= 14728 - 4312
= 10416 cm
3 Base area of Tank M
= 18 x 14
= 252 cm
2 Base area of Tank N
= 28 x 22
= 616 cm
2 Combined base areas of both tanks
= 252 + 616
= 868 cm
2 Height of water in Tank M
= 10416 ÷ 868
= 12 cm
(b)
Decrease in the height of Tank N after some water was poured out
= 4928 ÷ 616
= 8 cm
Original height of water before some was poured out
= 12 + 7
= 19 cm
Height of water after some was poured out
= 19 - 8
= 11 cm
Height of Tank M
= 2 x 11
= 22 cm
Answer(s): (a) 12 cm; (b) 22 cm