PSLE There was a total of 15520 cm
3 of water in rectangular tanks C and D at first. The height of the water level in tank D was 2 cm above that of tank C.
- Find the height of the water level in tank C.
- Xandra poured 2400 cm3 of water out of tank D. Tank D was then half filled with water. What was the height of tank D?
(a)
Volume of water in Tank D with a height of 2 cm
= 25 x 16 x 2
= 800 cm
3 Volume of water in both tanks excluding the water that is 2 cm above that of Tank C
= 15520 - 800
= 14720 cm
3 Base area of Tank C
= 21 x 16
= 336 cm
2 Base area of Tank D
= 25 x 16
= 400 cm
2 Combined base areas of both tanks
= 336 + 400
= 736 cm
2 Height of water in Tank C
= 14720 ÷ 736
= 20 cm
(b)
Decrease in the height of Tank D after some water was poured out
= 2400 ÷ 400
= 6 cm
Original height of water before some was poured out
= 20 + 2
= 22 cm
Height of water after some was poured out
= 22 - 6
= 16 cm
Height of Tank C
= 2 x 16
= 32 cm
Answer(s): (a) 20 cm; (b) 32 cm