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

A1/3
B6

c)3/2

d)2/3

Verified Answer :

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) \(\frac{2}{3}\)

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:

\(P(NotBlue)= 1 - P(Blue)\)

Where \(P(Blue)\) is the probability of removing a blue marble, which is:

\(P(Blue)=\frac{BlueMarbles}{TotalMarbles} =\frac{3}{9} =\frac{1}{3}\)

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

\(P(NotBlue)= 1 -\frac{1}{3}=\frac{2}{3}\)

Another way to reach the same result is as follows:

\(P(NotBlue)=P(Red) + P(Green)\)

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

\(P(Red)=\frac{RedMarbles}{TotalMarbles} =\frac{5}{9}\)

\(P(Green)=\frac{GreenMarbles}{TotalMarbles} =\frac{1}{9}\)

Thus:

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

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