PSLE There was a total of 34294 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.
- Betty poured 6435 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
= 39 x 33 x 3
= 3861 cm
3 Volume of water in both tanks excluding the water that is 3 cm above that of Tank C
= 34294 - 3861
= 30433 cm
3 Base area of Tank C
= 34 x 31
= 1054 cm
2 Base area of Tank D
= 39 x 33
= 1287 cm
2 Combined base areas of both tanks
= 1054 + 1287
= 2341 cm
2 Height of water in Tank C
= 30433 ÷ 2341
= 13 cm
(b)
Decrease in the height of Tank D after some water was poured out
= 6435 ÷ 1287
= 5 cm
Original height of water before some was poured out
= 13 + 3
= 16 cm
Height of water after some was poured out
= 16 - 5
= 11 cm
Height of Tank C
= 2 x 11
= 22 cm
Answer(s): (a) 13 cm; (b) 22 cm