Answer:
P(red and blue) = 1/12
Step-by-step explanation:
A probability is the number of desired outcomes divided by the number of total outcomes.
Probability of independent events:
If two events, A and B, are independent, the probability of both happening is the multiplication of the probabilities of each event happening, that is:
[tex]P(A \cap B) = P(A)P(B)[/tex]
P (red and blue).
Probability of choosing a red marble, then a blue marble. The marbles are replaced, so the trials are independent.
Probability of a red marble:
3 out of 3 + 5 + 4 = 12. So
[tex]P(A) = \frac{3}{12} = \frac{1}{4}[/tex]
Probability of a blue marble:
4 out of 12, so:
[tex]P(B) = \frac{4}{12} = \frac{1}{3}[/tex]
P (red and blue).
[tex]P(A \cap B) = P(A)P(B) = \frac{1}{4} \times \frac{1}{3} = \frac{1}{4*3} = \frac{1}{12}[/tex]
So
P(red and blue) = 1/12