Respuesta :
Answer:
0.3844 = 38.44% probability that two independently surveyed voters would both be Democrats
Step-by-step explanation:
For each voter, there are only two possible outcomes. Either the voter is a Democrat, or he is not. The probability of the voter being a Democrat is independent of other voters. So we use the binomial probability distribution to solve this question.
Binomial probability distribution
The binomial probability is the probability of exactly x successes on n repeated trials, and X can only have two outcomes.
[tex]P(X = x) = C_{n,x}.p^{x}.(1-p)^{n-x}[/tex]
In which [tex]C_{n,x}[/tex] is the number of different combinations of x objects from a set of n elements, given by the following formula.
[tex]C_{n,x} = \frac{n!}{x!(n-x)!}[/tex]
And p is the probability of X happening.
62% of the voters are Democrats
This means that [tex]p = 0.62[/tex]
(a) What is the probability that two independently surveyed voters would both be Democrats?
This is P(X = 2) when n = 2. So
[tex]P(X = x) = C_{n,x}.p^{x}.(1-p)^{n-x}[/tex]
[tex]P(X = 2) = C_{2,2}.(0.62)^{2}.(0.38)^{0} = 0.3844[/tex]
0.3844 = 38.44% probability that two independently surveyed voters would both be Democrats
