A bag contains 7 red marbles, 2 blue marbles, and 1 green marble. If a marble is selected at random, what is the probability of choosing a marble that is not blue?

I have seen so many different answers on this site to this question and am not sure. I thought it would be 7 red +1 green gives 8/10=4/5.

Our choices for the answer is 4/5,1/5, 5/4, 8

Right! 4/5 it is!

To find the probability of choosing a marble that is not blue, you need to calculate the number of favorable outcomes (marbles that are not blue) and divide it by the total number of possible outcomes (all the marbles in the bag).

In this case, the number of favorable outcomes (marbles that are not blue) is the sum of the number of red marbles and the number of green marbles, which is 7 + 1 = 8.

The total number of possible outcomes is the sum of all the marbles in the bag, which is 7 + 2 + 1 = 10.

So, the probability of choosing a marble that is not blue is 8/10, which simplifies to 4/5.

Therefore, the correct answer is 4/5.