Sunday, November 13, 2005
Any bird watchers out there?
Abel, Mabel, and Calib went bird watching. Each of them saw one bird that none of the others did. Each pair saw one bird that the third did not. And one bird was seen by all three. Of the birds Abel saw, two were yellow. Of the birds Mabel saw, three were yellow. Of the birds Calib saw, four were yellow. How many yellow birds were seen in all? How many non-yellow birds were seen in all?