Analyzing the Individual Probability Constraints
In the realm of probability, the likelihood of any event must be strictly confined between 0 and 1. For events A,B, and C defined by variable x, we must ensure each individual probability satisfies this axiom.
For event
A, where
P(A)=33x+1, we set:
0≤33x+1≤1
Multiplying by
3 gives
0≤3x+1≤3. Subtracting
1 and dividing by
3, we find the first boundary:
x∈[−31,32]
For event
B, where
P(B)=41−x, we enforce:
0≤41−x≤1
Multiplying by
4 gives
0≤1−x≤4. Subtracting
1 results in
−1≤−x≤3. Multiplying by
−1 flips the inequality signs, yielding the second boundary:
x∈[−3,1]
For event
C, where
P(C)=21−2x, we set:
0≤21−2x≤1
Multiplying by
2 gives
0≤1−2x≤2. Subtracting
1 yields
−1≤−2x≤1. Dividing by
−2 and flipping the signs, we arrive at the third boundary:
x∈[−21,21]
The Collective Constraint
Since events A,B, and C are mutually exclusive, the probability of their union is the sum of their individual probabilities. This total sum must also satisfy the axiom P(A∪B∪C)≤1.
We perform the summation:
33x+1+41−x+21−2x≤1
Using the least common multiple of
12, the inequality becomes:
124(3x+1)+3(1−x)+6(1−2x)≤1
Expanding the numerators, we observe:
1212x+4+3−3x+6−12x≤1
1213−3x≤1
Multiplying by
12 gives
13−3x≤12, which simplifies to
1≤3x. Thus, we obtain the final condition:
x≥31
Final Intersection of Conditions
To find the valid range for x, we must find the intersection of all four established conditions:
1. x∈[−31,32]
2. x∈[−3,1]
3. x∈[−21,21]
4. x∈[31,∞)
By comparing the lower bounds, the maximum is 31. By comparing the upper bounds, the minimum is 21.
Therefore, the valid interval for
x is:
x∈[31,21]