PSLE There was a total of 20070 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.
- Gillian poured 5152 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
= 32 x 23 x 5
= 3680 cm
3 Volume of water in both tanks excluding the water that is 5 cm above that of Tank M
= 20070 - 3680
= 16390 cm
3 Base area of Tank M
= 29 x 26
= 754 cm
2 Base area of Tank N
= 32 x 23
= 736 cm
2 Combined base areas of both tanks
= 754 + 736
= 1490 cm
2 Height of water in Tank M
= 16390 ÷ 1490
= 11 cm
(b)
Decrease in the height of Tank N after some water was poured out
= 5152 ÷ 736
= 7 cm
Original height of water before some was poured out
= 11 + 5
= 16 cm
Height of water after some was poured out
= 16 - 7
= 9 cm
Height of Tank M
= 2 x 9
= 18 cm
Answer(s): (a) 11 cm; (b) 18 cm