Respuesta :
Answer:
a) 0.34 = 35% probability that at least one member of a married couple will vote.
b) 0.7143 = 71.43% probability that a wife will vote
c) 0.0968 = 9.68% probability that a husband will vote
Step-by-step explanation:
Conditional Probability
We use the conditional probability formula to solve this question. It is
[tex]P(B|A) = \frac{P(A \cap B)}{P(A)}[/tex]
In which
P(B|A) is the probability of event B happening, given that A happened.
[tex]P(A \cap B)[/tex] is the probability of both A and B happening.
P(A) is the probability of A happening.
This is used for itens B and C. For item a, we treat the probabilities as Venn sets.
A) What is the probability that at least one member of a married couple will vote?
I am going to say that:
Event A: Husband votes.
Event B: Wife votes.
The probability that the husband will vote on a bond referendum is 0.21
This means that [tex]P(A) = 0.21[/tex]
The probability that the wife will vote on the referendum is 0.28
This means that [tex]P(B) = 0.28[/tex]
The probability that both the husband and the wife will vote is 0.15.
This means that [tex]P(A \cap B) = 0.15[/tex]
At least one votes:
This is [tex]P(A \cup B)[/tex], which is given by:
[tex]P(A \cup B) = P(A) + P(B) - P(A \cap B)[/tex]
So
[tex]P(A \cup B) = 0.21 + 0.28 - 0.15[/tex]
[tex]P(A \cup B) = 0.34[/tex]
0.34 = 35% probability that at least one member of a married couple will vote.
B) What is the probability that a wife will vote, given that her husband will vote?
Here, we use conditional probability:
Event A: Husband votes:
Event B: Wife votes
The probability that the husband will vote on a bond referendum is 0.21
This means that [tex]P(A) = 0.21[/tex]
Intersection of events A and B:
Intersection between husband voting and wife voting is both voting, which means that [tex]P(A \cap B) = 0.15[/tex]
The desired probability is:
[tex]P(B|A) = \frac{P(A \cap B)}{P(A)} = \frac{0.15}{0.21} = 0.7143[/tex]
0.7143 = 71.43% probability that a wife will vote.
C) What is the probability that a husband will vote, given that his wife does not vote?
Event A: Wife does not vote.
Event B: Husband votes.
The probability that the wife will vote on the referendum is 0.28
So 1 - 0.28 = 0.62 probability that she does not vote, which means that [tex]P(A) = 0.62[/tex]
Probability of husband voting and wife not voting:
0.21 probability husband votes, 0.15 probability wife votes, so 0.21 - 0.15 = 0.06 probability husband votes and wife does not, so [tex]P(A \cap B) = 0.06[/tex]
The desired probability is:
[tex]P(B|A) = \frac{P(A \cap B)}{P(A)} = \frac{0.06}{0.62} = 0.0968[/tex]
0.0968 = 9.68% probability that a husband will vote
