A bag contains 5 red marbles, 3 blue marbles, and 1 green marble. If one marble is removed from the bag, find the probability that it is NOT blue
a) 1/3
b) 6
c)3/2
d)2/3

Respuesta :

The answer is d) 2/3 because there are 9 marbles in the bag, and 6 of them are not blue, so the probability would be 6/9, which simplified is 2/3

Answer:

d) [tex]\frac{2}{3}[/tex]

Step-by-step explanation:

We have the following information:

  • 5 red marbles
  • 3 blue marbles
  • 1 green marble

total of marbles: 5 + 3 + 1 = 9

The probability of removing one marble from the bag and not being blue is:

[tex]P(NotBlue)= 1 - P(Blue)[/tex]

Where [tex]P(Blue)[/tex] is the probability of removing a blue marble, which is:

[tex]P(Blue)=\frac{BlueMarbles}{TotalMarbles} =\frac{3}{9} =\frac{1}{3}[/tex]

So, the probability of removing one marble that is not blue, is the total probability (1) minus the probability of removing a blue marble:

[tex]P(NotBlue)= 1 -\frac{1}{3}=\frac{2}{3}[/tex]

Another way to reach the same result is as follows:

[tex]P(NotBlue)=P(Red) + P(Green)[/tex]

Since it can't be a blue one, we add the chances of it coming out red or green.

[tex]P(Red)=\frac{RedMarbles}{TotalMarbles} =\frac{5}{9}[/tex]

[tex]P(Green)=\frac{GreenMarbles}{TotalMarbles} =\frac{1}{9}[/tex]

Thus:

[tex]P(NotBlue)=P(Red) + P(Green)=\frac{5}{9}+\frac{1}{9}=\frac{6}{9}=\frac{2}{3}[/tex]

Which is the same result we had found, so those are two ways of finding the answer to this problem.

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