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Suppose you choose a marble from a bag containing 3 red marbles, 5 white marbles, and 4 blue
marbles. You return the first marble to the bag and then choose again. Find P (red and blue).


Sagot :

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