Bizarre AP Stats Concept

<p>Hey guys,</p>

<p>I don't understand this portion of chapter six at all. It's got to be right under my nose but I don't get it. Can someone explain to me this problem?</p>

<p>A box contains one red, three blue, and two green marbles. Two marbles are selected in succession (i.e., without replacement) at random. Find the probability (P(D)) that at least one of the marbles is blue.</p>

<p>This is what I did
P(D) = P(at least one of the marbles is blue)
P(both marbles are blue) = (2/6)(2/5) = .200
P(first marble is blue) = (3/6)(5/5) = .500
P(second marble is blue) = (6/6)(3/5) = .600
.200 + .500 + .600 = 1.300 = HUGE PROBLEM</p>

<p>What am I missing here?</p>

<p>applicannot</p>

<p>Of course, on the eighth page of Google results, I got it. Sorry.</p>