Answer:
3/28
Step-by-step explanation:
There are 14 marbles in the bag. So, the probability of choosing a blue marble is 7/14 or 1/2. Since the first marble is replaced, the bag still has 14 marbles in it. Then the probability of choosing a red marble is 3/14. The probability of choosing the blue, then the red is 1/2 x 3/14 = 3/28