Probability question with combinations of different types of an item Suppose a bakery has 18 varieties of bread, one of which is blueberry bread. If a half dozen loafs of bread are selected at random (with repetitions allowed), then what is the probability that at least one of the loafs of blueberry bread will be included in the selection.
I started off by determining that if we picked up at least one blueberry bread from the start, then we could find the total ways by finding:
$C_{R}(n, r)$
Plugging in for $n$ and $r$ I calculated that the number of ways would be:
$C_{R}(18, 5) = C(18+5-1,5) = 26,344$ ways.
Am I on the right track, and how would I go about finding the probability in this case?

6 loaves of bread are selected with repetitions allowed.  Therefore, there are $18^6$ possible lists of bread without any restraints. Now if we included the condition that at least one of them is blueberry, it would be easier to approach the question from the converse.  The opposite of at least one of them being blueberry is none being blueberry. There are $17^6$ possible choices in which none of the six bread is blueberry, and therefore $18^6-17^6$ choices where at least one is blueberry. So now we have the answer,
$$(18^6-17^6)/18^6 = 0.29$$
