Answer: 33.33%
Explanation:
why You can just use some sort of counting principle
The first time you draw a read marble, your odds of getting 1 were 4/7
You are not replacing the marble. Your choice now is 3/6
now if there is 6 in all left than 2 marbles that are blue would be 1/3 or 33.33 in percent so it would be not likely