Respuesta :
The probability of the union of being either a freshman or junior is 0.50
What is probability?
"Probability is a branch of mathematics which deals with finding out the likelihood of the occurrence of an event."
Formula of the probability of an event A is:
P(A) = n(A)/n(S)
where, n(A) is the number of favorable outcomes,
n(S) is the total number of events in the sample space.
For given example,
Students have equal probabilities of being freshmen, sophomores, juniors, or seniors.
⇒ P(freshman) = 0.25
⇒ P(sophomores) = 0.25
⇒ P(juniors) = 0.25
⇒ P(seniors) = 0.25
We know for event A and B,
P(A ∪ B) = P(A) + P(B) - P(A ∩ B)
Assuming event A : student is a freshman
event B : student is junior
P(A) = 0.25
P(B) = 0.25
The number of students who are freshman as well as junior = 0
⇒ n(A ∩ B) = 0
⇒ P(A ∩ B) = 0
Now, the probability of the union of being either a freshman or junior would be,
⇒ P(A ∪ B) = P(A) + P(B) - P(A ∩ B)
⇒ P(A ∪ B) = 0.25 + 0.25 - 0
⇒ P(A ∪ B) = 0.50
Therefore, the probability of the union of being either a freshman or junior is 0.50
Learn more about probability here:
brainly.com/question/11234923
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