4834. There are n=27 parts in a box, among which a=20 are painted. Two parts are taken out at random. Find the probability that:
1) both removed parts will be painted;
2) one part is painted and the other is unpainted (the order of appearance of parts is not taken into account);
3) at least one of the two parts will be painted.
Detailed solution. Decorated in Microsoft Word 2003 (Quest decided to use the formula editor)
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