PSLE There was a total of 21096 cm
3 of water in rectangular tanks R and S at first. The height of the water level in tank S was 3 cm above that of tank R.
- Find the height of the water level in tank R.
- Yen poured 5544 cm3 of water out of tank S. Tank S was then half filled with water. What was the height of tank S?
(a)
Volume of water in Tank S 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 R
= 21096 - 2376
= 18720 cm
3 Base area of Tank R
= 24 x 19
= 456 cm
2 Base area of Tank S
= 33 x 24
= 792 cm
2 Combined base areas of both tanks
= 456 + 792
= 1248 cm
2 Height of water in Tank R
= 18720 ÷ 1248
= 15 cm
(b)
Decrease in the height of Tank S after some water was poured out
= 5544 ÷ 792
= 7 cm
Original height of water before some was poured out
= 15 + 3
= 18 cm
Height of water after some was poured out
= 18 - 7
= 11 cm
Height of Tank R
= 2 x 11
= 22 cm
Answer(s): (a) 15 cm; (b) 22 cm