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392
1#
發表於 10-5-30 11:52 |只看該作者 |倒序瀏覽 |打印
1.An aquarium measures 36 cm long, 22 cm wide and 25 cm high (inside measurements), contains 1296cm3 of sand.How much water is poured into it if the water level is 20 cm high?

2.How much will the water level rise if a brick 20 cm by 8 cm by 8cm is put inside an aquarium 32 cm long, 30cm wide and 28 cm high (inside measurements)?

各位高人,請教吓我呢兩題數,我仔明天test,佢唔明,我都唔識教佢,可唔可以解釋我知點計.唔該!!!
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Rank: 2


48
2#
發表於 10-5-30 21:24 |只看該作者
原帖由 pingubj 於 10-5-30 11:52 發表
1.An aquarium measures 36 cm long, 22 cm wide and 25 cm high (inside measurements), contains 1296cm3 of sand.How much water is poured into it if the water level is 20 cm high?

2.How much will the wat ...


1. Let x cm be the amount of water,

1296 + x = 36 X 22 X 20
            x = 14544

14544ml of water is poured into it.


2. Let the water rise x cm,

20 X 8 X 8 = 32 X 30 X x
        1280 = 960x
              x = 4/3 (= 1.33333333......)

the water rise 4/3 cm.

Rank: 3Rank: 3


392
3#
發表於 10-6-1 15:29 |只看該作者
thanks

如果唔用方程,可以點計

[ 本帖最後由 pingubj 於 10-6-1 15:30 編輯 ]

Rank: 2


80
4#
發表於 10-6-1 21:27 |只看該作者
1. 20cm x 36 cm x 22 cm -1296 = 14544
(i.e. volume of water need to fill the aquarium with 20 cm high minus volume of sand)

2. (20cm x 8cm x 8 cm) / (32cm x 30cm) = 1280/960= 4/3
i.e. volume of brick divided by base area of aquarium

Rank: 5Rank: 5


3047
5#
發表於 10-6-4 00:18 |只看該作者
No. 1, Be careful,
a cup of sand + a cup of water
not equal to 2 cups of sand water,
You may try. If you don't have sand, you may pour some water to a full cup of rice.
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