1. Determine the
Probability by sample
If S is a sample space and A is an event in the
sample space, then the probability of A happening is:
P(A)=
Range of probability value is: 0 P(A) 1
P(A) = 1 is called a certain event
P(A) = 0 is called an impossible event
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An

2. Example :
Look at the event of dice throwing.
The outcomes possibility are 1, 2, 3, 4, 5, or 6.
So the sample space is S= {1,2,3,4,5,6}
Suppose the outcomes of even spots dice is
E={2,4,6}.
The number of set E is denoted by n(E),
so n(E)=3

3. We use the way as follow:
S= {1,2,3,4,5,6} , so n(S) = 6
E= {2,4,6} , so n(E)= 3
P(E)= 2
1
6
3
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4. EXERCISE
there is a dice that will be
tossed. Determine the
probability of appearing:
a. 2
b. Numbers in a dice that
less than 4
c. 7
d. 1, 2, 3, 4, 5, or 6

5. Expected frequency of an event is a probability
that is done in many times. If A is an event of
an experiment and this experiment is done n
times then the probability of event A in n
experiments is :
Expected frequency
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6. Example :
1. A coin which consists of the number side and the picture side
tossed 100 times. How many the probability of appearing number
side?
Answer : If the coin is tossed 1 time, the probability of appearing
picture side is 1 / 2. Because the probability of appearing of picture
side for 1 time tossed is 1 / 2, then for tossed 100 times, we will get
:
50100
2
1
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AF
nAPAF
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