91影视

Assume there are 5 balls. 2 of them are red in colour and the others are green.

A = Two red balls are drawn

B = A red and a green ball is drawn

C = Two green balls are drawn

$\mathbf{n}\left(\mathbf{A}\right)\mathbf{=}\mathbf{23}\mathbf{,}\mathbf{n}\left(\mathbf{B}\right)\mathbf{=}\mathbf{37}\mathbf{,}\mathbf{n}\left(\mathbf{C}\right)\mathbf{=}\mathbf{17}\mathbf{,}\mathbf{n}\left(\mathbf{S}\right)\mathbf{=}\mathbf{100}$

Therefore, $\mathbf{P}\left(\mathbf{A}\right)\mathbf{=}\mathbf{0}\mathbf{.}\mathbf{23}\mathbf{,}\mathbf{P}\left(\mathbf{B}\right)\mathbf{=}\mathbf{0}\mathbf{.}\mathbf{37}\mathbf{,}\mathbf{P}\left(\mathbf{C}\right)\mathbf{=}\mathbf{0}\mathbf{.}\mathbf{17}$

The probabilities calculated in exercise 3.7 for events A, B and C were $\mathbf{P}\left(\mathbf{A}\right)\mathbf{=}\frac{\mathbf{1}}{\mathbf{8}}\mathbf{=}\mathbf{0}\mathbf{.}\mathbf{125}\mathbf{,}\mathbf{P}\left(\mathbf{B}\right)\mathbf{=}\frac{\mathbf{3}}{\mathbf{8}}\mathbf{=}\mathbf{0}\mathbf{.}\mathbf{375}$and $\mathbf{P}\left(\mathbf{C}\right)\mathbf{=}\frac{\mathbf{1}}{\mathbf{2}}\mathbf{=}\mathbf{0}\mathbf{.}\mathbf{5}$.

Doing the simulation run for drawing two balls from 5 balls sample space, one gets $\mathbf{P}\left(\mathbf{A}\right)\mathbf{=}\mathbf{0}\mathbf{.}\mathbf{11}\mathbf{,}\mathbf{P}\left(\mathbf{B}\right)\mathbf{=}\mathbf{0}\mathbf{.}\mathbf{39}$ and $\mathbf{P}\left(\mathbf{C}\right)\mathbf{=}\mathbf{0}\mathbf{.}\mathbf{16}$ .

Here, one observes that probabilities calculated in exercise 3.7 and the probabilities calculated here are near to each other. That is because of the Law of Large Numbers.

Law of large number states that when an experiment is conducted repeatedly, the possibility of the number of times an event will occur approaches the theoretical probability of the outcome.

Repeating the experiment, say 100 times gives the possibility for events A, B and C as close to its theoretical probability which is calculated in exercise 3.7.

In exercise 3.7, the probability of events A, B and C were $\mathbf{P}\left(\mathbf{A}\right)\mathbf{=}\frac{\mathbf{1}}{\mathbf{8}}\mathbf{=}\mathbf{0}\mathbf{.}\mathbf{125}\mathbf{,}\mathbf{P}\left(\mathbf{B}\right)\mathbf{=}\frac{\mathbf{3}}{\mathbf{8}}\mathbf{=}\mathbf{0}\mathbf{.}\mathbf{375}$ and $\mathbf{P}\left(\mathbf{C}\right)\mathbf{=}\frac{\mathbf{1}}{\mathbf{2}}\mathbf{=}\mathbf{0}\mathbf{.}\mathbf{5}$.

While after running the simulation 100 times we get the possibility of events A, B and C happening as, $\mathbf{P}\left(\mathbf{A}\right)\mathbf{=}\mathbf{0}\mathbf{.}\mathbf{11}\mathbf{,}\mathbf{P}\left(\mathbf{B}\right)\mathbf{=}\mathbf{0}\mathbf{.}\mathbf{39}$and $\mathbf{P}\left(\mathbf{C}\right)\mathbf{=}\mathbf{0}\mathbf{.}\mathbf{16}$. If one simulates let鈥檚 say 1000 times, the possibility of these events happening will get closer to the theoretical probability.