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 Question from alan: An employer must select three people for layoff from three groups. Group 1 has 4 members and the oldest member is selected. Group 2 has 7 members and the oldest member is selected. Group 3 has 2 members and the younger is selected. Assuming equal qualifications, w vs. biased as to age? What is the formula to determine this?

Hi Alan,

There are 4 people in the first group, 7 in the second and 2 in the third so if you are to select one person from each group there are 4 7 2 = 56 possible selections. If the selection process was random, that is you randomly selected one person from each group then the probability that your process resulted in the eldest from the first two groups and the younger from the third group is 1/56.

This however does not seem to be the question you are asking. It seems that you are asking "If the selection procedure produced the eldest from the first two groups and the younger from the third group what is the probability that the selection procedure was random?" The selection procedure was either random or not and you have no way to decide this based on the particular selections that were made. To determine wherher the procedure was random or not you need to know how the selections were made. The particular result gives you no information on the procedure used.

Penny

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