PSLE There was a total of 16000 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.
- Jen poured 3360 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
= 28 x 20 x 5
= 2800 cm
3 Volume of water in both tanks excluding the water that is 5 cm above that of Tank N
= 16000 - 2800
= 13200 cm
3 Base area of Tank N
= 20 x 16
= 320 cm
2 Base area of Tank P
= 28 x 20
= 560 cm
2 Combined base areas of both tanks
= 320 + 560
= 880 cm
2 Height of water in Tank N
= 13200 ÷ 880
= 15 cm
(b)
Decrease in the height of Tank P after some water was poured out
= 3360 ÷ 560
= 6 cm
Original height of water before some was poured out
= 15 + 5
= 20 cm
Height of water after some was poured out
= 20 - 6
= 14 cm
Height of Tank N
= 2 x 14
= 28 cm
Answer(s): (a) 15 cm; (b) 28 cm