咁多位,我又黎問probability啦~T^T

你好叻,我完全唔明呀!
你讀幾年級?

我都讀過A. MATHS. 喎，點解我全部都唔識嘅？
俾番晒老師？

八王爺 發表於 2011-10-13 12:17
我都讀過A. MATHS. 喎，點解我全部都唔識嘅？
俾番晒老師？

我都俾返哂阿Sir.  都唔敢答chingyi的問題.

chingyi, 不如你由基礎開始教返我哋吖.

比得大帝 發表於 2011-10-13 14:48
我都俾返哂阿Sir.  都唔敢答chingyi的問題.

chingyi, 不如你由基礎開始教返我哋吖.  ...

唔敢當唔敢當~
haha~其實我係咁意都講左小小關於nCr同nPr嗰D野,係#15

比得大帝 發表於 2011-10-13 14:48
我都俾返哂阿Sir.  都唔敢答chingyi的問題.

chingyi, 不如你由基礎開始教返我哋吖.  ...

probability即係概率啦,以下會用P(x)黎表示
最簡單嘅係擲1粒公平嘅dice 假如我地依家要係1個擲到6嘅話,咁P(擲6)=1/6(因為1粒dice有6面)
難DD,要擲2次而2次都係要出到6嘅話,就會係咁(6)*P(6)=(1/6)(1/6)=1/36
再難DD,擲2次,要得1次係6嘅話,就係咁:2C1P(6)P(1-5)=2*(1/6)*(5/6)=5/18
以上嘅....會唔會remind到你地小小嘅記憶呢?haha

上面有人提出了 probability 不可靠的問題。我對讀 probability 的理解是：

多數人以為 probability 的用處在於它的的預測性。當低 probability 的事件發生時會感到失望。其實 probability 和 statistic 有非常緊密的關係。Probability 的作用在於 benchmarking，使我們知道 statistical data 出了偏差。所以讀 M1 的和讀 stat 的要讀好 probability 呀！^^

孖吉 發表於 2011-10-13 20:42
上面有人提出了 probability 不可靠的問題。我對讀 probability 的理解是：

多數人以為 probability 的用 ...

所以我每晚都要同probability死過嘅probability係1

chingyi724 發表於 2011-10-13 20:51
所以我每晚都要同probability死過嘅probability係1

哈哈，好好笑呀^^"

姐姐，我想問您Chemistry,點解sodium chloride 加 water會conducts 到electricity ge?

唔系話只系molten state ge ionic substances會conducts electricity,點解sodium chloride 唔系ge?

marcolmh929 發表於 2011-10-13 21:00
姐姐，我想問您Chemistry,點解sodium chloride 加 water會conducts 到electricity ge?

因為當佢變左做liquid之後會有free electron

chingyi724 發表於 2011-10-13 21:04
因為當佢變左做liquid之後會有free electron

點解會有free e-?

marcolmh929 發表於 2011-10-13 21:05
點解會有free e-?

因為佢係electrolyte

chingyi724 發表於 2011-10-13 21:08
因為佢係electrolyte

但系唔break 個 ionic bond,點會有free ions 呀？無free ions 點會叫electrolyte呀？

marcolmh929 發表於 2011-10-13 21:09
但系唔break 個 ionic bond,點會有free ions 呀？無free ions 點會叫electrolyte呀？

sodium chloride係ionic compounds黎嫁嘛~所有ionic compounds係molten state或係liquid state嘅底下都係有free electron

marcolmh929 發表於 2011-10-13 21:09
但系唔break 個 ionic bond,點會有free ions 呀？無free ions 點會叫electrolyte呀？

抄返來的：
Solution conductivity

Electrons are not the only particles capable of carrying an electric current. Ions can do it, too. An ion is an atom or group of atoms with an electric charge. Suppose you dissolve a crystal of table salt (sodium chloride) in water. Salt crystals consist of positive sodium ions and negative chloride ions. In the solid state, these ions are not free to move around. Once they are dissolved in water, however, they become completely mobile. They are free to "swim" about in the water and to respond to an electric current from a battery. That current supplies electrons that cause positive sodium ions to flow in one direction and negative chloride ions to flow in the opposite direction.

A good example of this effect can be seen in the conductivity of water. Pure water consists only of water molecules. The electrons in water molecules are held tightly by hydrogen and oxygen atoms and are not free to move. Attaching a battery to a container of water produces no electric current because pure water is an insulator. But a few grains of table salt added to the water changes things completely. Sodium ions and chloride ions are released from the salt, and the salt water solution becomes conductive.

marcolmh929
係wo 應該話係aq先岩
我Dchem真係差到冇朋友

chingyi724 發表於 2011-10-13 21:13
sodium chloride係ionic compounds黎嫁嘛~所有ionic compounds係molten state或係liquid state嘅底下都係 ...

禁有無d ionic substances系唔溶於水（唔可以AQ ga?)
唔該曬您

marcolmh929 發表於 2011-10-13 21:20
禁有無d ionic substances系唔溶於水（唔可以AQ ga?)
唔該曬您

1定有,但我唔知
遲D得閒問下呀sir先