Final answer:
The probability of choosing one blue ball then a yellow ball with replacement is 1/8, or 0.125.
Step-by-step explanation:
To find the probability of choosing one blue ball and then one yellow ball with replacement, we need to calculate the probability of each event separately and then multiply them together.
The probability of choosing a blue ball is 6/(6+3+3) = 6/12 = 1/2.
Since the ball is replaced, the probability of choosing a yellow ball is also 3/(6+3+3) = 3/12 = 1/4.
Therefore, the probability of choosing one blue ball then a yellow ball with replacement is (1/2) * (1/4) = 1/8, or 0.125.