PSLE There was a total of 25074 cm
3 of water in rectangular tanks R and S at first. The height of the water level in tank S was 6 cm above that of tank R.
- Find the height of the water level in tank R.
- Gabby poured 4557 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 6 cm
= 31 x 21 x 6
= 3906 cm
3 Volume of water in both tanks excluding the water that is 6 cm above that of Tank R
= 25074 - 3906
= 21168 cm
3 Base area of Tank R
= 25 x 21
= 525 cm
2 Base area of Tank S
= 31 x 21
= 651 cm
2 Combined base areas of both tanks
= 525 + 651
= 1176 cm
2 Height of water in Tank R
= 21168 ÷ 1176
= 18 cm
(b)
Decrease in the height of Tank S after some water was poured out
= 4557 ÷ 651
= 7 cm
Original height of water before some was poured out
= 18 + 6
= 24 cm
Height of water after some was poured out
= 24 - 7
= 17 cm
Height of Tank R
= 2 x 17
= 34 cm
Answer(s): (a) 18 cm; (b) 34 cm