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 blues?

Answer 1

Answer:

1/11

Step-by-step explanation

There are 12 marbles in the bag. When we first pick we have 4 blue marbles. So 4 blue marbles/12 random marbles. When we pick blue and noted, there are 3 marbles in the bag because of we didn't put it back. So when we choose again there are 11 marbles and 3 blue marbles in the bag. Choosing a blue one case is 3/11.

The last part of this case is happening as a chain. So we need to multiply our two answers.

=4/12*3/11

=1/3*3/11

=1/11