PSLE There was a total of 18000 cm
3 of water in rectangular tanks N and P at first. The height of the water level in tank P was 5 cm above that of tank N.
- Find the height of the water level in tank N.
- Elyse poured 4320 cm3 of water out of tank P. Tank P was then half filled with water. What was the height of tank P?
(a)
Volume of water in Tank P with a height of 5 cm
= 30 x 24 x 5
= 3600 cm
3 Volume of water in both tanks excluding the water that is 5 cm above that of Tank N
= 18000 - 3600
= 14400 cm
3 Base area of Tank N
= 24 x 20
= 480 cm
2 Base area of Tank P
= 30 x 24
= 720 cm
2 Combined base areas of both tanks
= 480 + 720
= 1200 cm
2 Height of water in Tank N
= 14400 ÷ 1200
= 12 cm
(b)
Decrease in the height of Tank P after some water was poured out
= 4320 ÷ 720
= 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 N
= 2 x 11
= 22 cm
Answer(s): (a) 12 cm; (b) 22 cm