PSLE There was a total of 25506 cm
3 of water in rectangular tanks N and P at first. The height of the water level in tank P was 3 cm above that of tank N.
- Find the height of the water level in tank N.
- Jane poured 3168 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 3 cm
= 33 x 24 x 3
= 2376 cm
3 Volume of water in both tanks excluding the water that is 3 cm above that of Tank N
= 25506 - 2376
= 23130 cm
3 Base area of Tank N
= 30 x 25
= 750 cm
2 Base area of Tank P
= 33 x 24
= 792 cm
2 Combined base areas of both tanks
= 750 + 792
= 1542 cm
2 Height of water in Tank N
= 23130 ÷ 1542
= 15 cm
(b)
Decrease in the height of Tank P after some water was poured out
= 3168 ÷ 792
= 4 cm
Original height of water before some was poured out
= 15 + 3
= 18 cm
Height of water after some was poured out
= 18 - 4
= 14 cm
Height of Tank N
= 2 x 14
= 28 cm
Answer(s): (a) 15 cm; (b) 28 cm