Answer:
The required probability is [tex]\frac{7}{9}[/tex].
Step-by-step explanation:
Set given is:
S = {1, 2, 3, 5, 15, 21, 29, 38, 500}
Total number of elements in set, [tex]n(S)[/tex] = 9
Let A be the event that the number is less than 29 ({1, 2, 3, 5, 15, 21}).
Number of items in the event A, [tex]n(A)[/tex] = 6
Probability of event A,
[tex]P(A) = \dfrac{n(A)}{n(S)}}=\dfrac{6}{9} \Rightarrow \dfrac{2}{3}[/tex]
Formula for probability of any event E:
[tex]P(E) = \dfrac{\text{Number of favorable cases}}{\text {Total number of cases}}[/tex]
Let B be the event that the number is odd (either of {1,3,5,15,21,29}).
Number of items in the event B, [tex]n(B)[/tex] = 6
Probability of event B,
[tex]P(B) = \dfrac{n(B)}{n(S)}}=\dfrac{6}{9} \Rightarrow \dfrac{2}{3}[/tex]
The event A and B have a few elements in common, i.e. numbers less than 29 which are odd as well.
The common elements are represented as:
[tex]A \cap B = \{1, 3, 5, 15, 21\}[/tex]
[tex]n(A\cap B) = 5[/tex]
[tex]P(A \cap B ) = \dfrac{n(A \cap B)}{n(s)}\\\Rightarrow P(A \cap B) = \dfrac{5}{9}[/tex]
To find probability of selecting a number which is either less than 29 (event A) or odd (event B),
We have to find [tex]P(A\ or \ B)[/tex] which is represented as [tex]P(A \cup B)[/tex] and the formula is:
[tex]P(A \cup B) = P(A) + P(B) - P(A \cap B)\\\Rightarrow \dfrac{2}{3} + \dfrac{2}{3} - \dfrac{5}{9}\\\Rightarrow \dfrac{12-5}{9}\\\Rightarrow \dfrac{7}{9}[/tex]
The required probability is [tex]\frac{7}{9}[/tex].
