Question

There is a bag filled with 2 blue, 4 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 the same colour?
IN FRACTION FORM PLEASS

Answer 1

`(17)/(55)`

Explanation:

After taking one of the 11 marbles, there are 10 marbles left.

Probability of blue followed by blue is

`(2)/(11) * (1)/(10) = (2)/(110)`

Probability of red followed by red is

`(4)/(11) * (3)/(10) = (12)/(110)`

Probability of green followed by green is

`(5)/(11) * (4)/(10) = (20)/(110)`

Adding these probabilities, we have

`(2 + 12 + 20)/(110) = (34)/(110) = (17)/(55)`