PSLE There was a total of 41430 cm
3 of water in rectangular tanks C and D at first. The height of the water level in tank D was 3 cm above that of tank C.
- Find the height of the water level in tank C.
- Tiffany poured 4200 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 3 cm
= 35 x 30 x 3
= 3150 cm
3 Volume of water in both tanks excluding the water that is 3 cm above that of Tank C
= 41430 - 3150
= 38280 cm
3 Base area of Tank C
= 32 x 27
= 864 cm
2 Base area of Tank D
= 35 x 30
= 1050 cm
2 Combined base areas of both tanks
= 864 + 1050
= 1914 cm
2 Height of water in Tank C
= 38280 ÷ 1914
= 20 cm
(b)
Decrease in the height of Tank D after some water was poured out
= 4200 ÷ 1050
= 4 cm
Original height of water before some was poured out
= 20 + 3
= 23 cm
Height of water after some was poured out
= 23 - 4
= 19 cm
Height of Tank C
= 2 x 19
= 38 cm
Answer(s): (a) 20 cm; (b) 38 cm