There are 100 balls in a container. 30 of them are red, 50 blue, and 20 green. We randomly select a ball, return it to the container and select another ball. What is the probability that both times balls are green?

Question

Write your answer as a decimal.

Answer 1

To find the probability that both times the balls selected are green, we start by identifying the probability of selecting a green ball in a single draw.

There are 20 green balls out of a total of 100 balls in the container. Thus, the probability \( P(\text{green}) \) of selecting a green ball on a single draw is:

\[ P(\text{green}) = \frac{20}{100} = 0.2 \]

Since we are drawing with replacement, the probability of selecting a green ball remains the same for each draw. Therefore, the probability of selecting two green balls consecutively is calculated as follows:

\[ P(\text{both green}) = P(\text{green}) \times P(\text{green}) = 0.2 \times 0.2 \]

Calculating the product:

\[ P(\text{both green}) = 0.2 \times 0.2 = 0.04 \]

Thus, the probability that both times the balls selected are green is:

\[ \boxed{0.04} \]