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 at least 1 red?
There are a total of 6 + 5 = 11 marbles in the bag.
The chance of not getting a red marble is 6/11 for one try.
With the second try, the chance of not getting a red marble is again 6/11.
Therefore, the probability of not getting a red marble on either try is 6/11 * 6/11 = 36/121
From here, the chance of getting a red marble on either try is 1 - (36/121) = 85/121.