Question 200169
You start with 13 marbles; 7 red, 6 green
You pull out on marble. What is the probability of being red?  7/13
Now you have 12 marbles left; 6 red, 6 green
Pull out another marble. What is the probability of being red?  6/12

What is the probability of both being red? {{{ (7/13) * (6/12)}}} You can simplify it. 

What if you put the original red one back before drawing a second time?
Both draws would have the same probability --> 7/13

So if you drew one marble, then put it back and drew a second time, the probability of both being red are
{{{(7/13) * (7/13)}}}