Question

There is a bag filled with 4 blue, 3 red and 5 green marbles.

A marble is taken at random from the bag, the colour is noted and then it is not replaced.
Another marble is taken at random.
What is the probability of getting 2 different colours?

Answer 1

.

green 0.416 red0.25 blue0.3

Explanation:

Answer 2

• 47/66 or 0.71 or 71%

Explanation:

• 4 blue, 3 red and 5 green marbles
• Total marbles = 12

Possible options for 2 different colors are:

• BR, BG, RB, RG, GB, GR

Probability of each:

• P(BR) = 4/12*3/11 = 1/11
• P(BG) = 4/12*5/11 = 5/33
• P(RB) = 3/12*4/11 = 1/11
• P(RG) = 3/12*5/11 = 5/44
• P(GB) = 5/12*4/11 = 5/33
• P(GR) = 5/12*3/11 = 5/44

Now, the probability of 2 different colors:

• P(2 different colors) =
• 1/11*2 + 5/33*2 + 5/44*2 =
• 2/11 + 10/33 + 5/22 =
• (2*6+ 10*2 + 5*3)/66 =
• 47/66 = 0.71 = 71%