a) The probability that the student has a sister is 0.4827.
b) The probability that the student has a sister is 0.3636.
Using the probability formula:
P = (Favorable event) / (Total event)
£ represents 29 students in class B represents students who have a brother S represents students who have a sister.
a) Then the equation will be given as,
7 + 4 + 2x + x + 3 = 29
3x = 29 - 14
3x = 15
x = 5
Substituting for x in 2x:
2x = 2(5)
2x = 10
The value of x + 3 is:
x + 3 = 5 + 3 = 8
The probability that the student has a sister will be
P = (10 + 4) / 29
P = 14 / 29
P = 0.4827
b) One of the students who has a brother is chosen at random. then the probability that this student has a sister will be
P = 4/11
P = 0.3636