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 replaced.
Another marble is taken at random.
What is the probability of getting exactly 1 blue?

Answer 1

The chances of receiving two greens are 5/31.

Given a bag containing four blue, three red, and five green marbles, the total result is:

Total number of balls = 4 + 3 + 5 = 12

If green is chosen first, the chances of picking a green are 5/12.

The probability that the second stone is green is 4/11 if it is picked and not replaced (4 greens remaining)

The chance of earning two greens is 5/12 4/11.

The chance of getting two greens is 20/132.

The chance of earning two greens is 5/31.

As a result, the chance of getting two greens is 5/31.