The probability of not picking a green ball is 1/2.

Here's the reasoning behind this:

1. There are a total of 20 balls in the bag (4 red + 6 blue + 10 green).
2. We want to find the probability of not picking a green ball, which means we need to consider the combined probability of picking either a red or a blue ball.
3. There are 4 red balls and 6 blue balls, for a total of 10 non-green balls.
4. So, the probability of picking a non-green ball is the number of non-green balls divided by the total number of balls: 10 non-green balls / 20 total balls.
5. This simplifies to a probability of 1/2.

Therefore, the probability of not picking a green ball is 1/2.
A bag contains 4 red balls, 6 blue balls, and 10 green balls. If you randomly pick one ball from the bag, what is the probability that it will not be a green ball?