PSLE There was a total of 29680 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.
- Opal poured 7280 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
= 35 x 26 x 7
= 6370 cm
3 Volume of water in both tanks excluding the water that is 7 cm above that of Tank M
= 29680 - 6370
= 23310 cm
3 Base area of Tank M
= 28 x 23
= 644 cm
2 Base area of Tank N
= 35 x 26
= 910 cm
2 Combined base areas of both tanks
= 644 + 910
= 1554 cm
2 Height of water in Tank M
= 23310 ÷ 1554
= 15 cm
(b)
Decrease in the height of Tank N after some water was poured out
= 7280 ÷ 910
= 8 cm
Original height of water before some was poured out
= 15 + 7
= 22 cm
Height of water after some was poured out
= 22 - 8
= 14 cm
Height of Tank M
= 2 x 14
= 28 cm
Answer(s): (a) 15 cm; (b) 28 cm