Question

There is a bag filled with 6 blue and 5 red 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 2 reds?

Answer 1

Explanation:

The first probability of it being red = 5/11

The key to the question is that you replace the red marble you took out. So there are still 5 red marbles.

You still have a 5/11 chance of getting a red marble.

P(red + red) = 5/11 * 5/11

Answer

P(red + red) = 25 / 121