The probability that a student chosen randomly from the class has a sister, in a class of 25 students, is 2/5.
For two events A and B, we have:
Probability that event A or B occurs = Probability that event A occurs + Probability that event B occurs - Probability that both the event A and B occur simultaneously.
This can be written symbolically as:
[tex]P(A \cup B) = P(A) + P(B) - P(A \cap B)[/tex]
For three events, A, B and C:
[tex]P(A \cup B \cup C) = P(A) + P(B) + P(C) - P(A\cap B) - P(A \cap C) - P(B \cap C) + P(A \cap B \cap C)[/tex]
In a class of 25 students, 16 have a brother and 10 have a sister. There are 6 students who have a brother and a sister.
Let A is event of a student having a brother and B is event of a student having a sister.
The probability of event A is,
[tex]P(A)=\dfrac{16}{25}[/tex]
The probability of event B is,
[tex]P(B)=\dfrac{10}{25}\\P(B)=\dfrac{2}{5}[/tex]
The probability of occurrence of both event A and B together,
[tex]P(A\cap B)=\dfrac{6}{25}[/tex]
Thus, the probability that a student chosen randomly from the class has a sister, in a class of 25 students, is 2/5.
Learn more about probability here:
brainly.com/question/1210781
#SPJ2
