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Let x be the total number of participants at the meeting.
Since 3 1 of the participants are men, the number of men is 3 x .
Since 2 1 of the participants are teachers, the number of teachers is 2 x .
Since 8 0 % of the teachers are women, the number of female teachers is 8 0 % of 2 x = 5 2 x .
The number of male teachers is the number of teachers minus the number of female teachers, which is 2 x − 5 2 x = 1 0 x .
Since 2 1 of the men are engineers, the number of male engineers is 2 1 ⋅ 3 x = 6 x .
The number of male doctors is the number of men minus the number of male teachers minus the number of male engineers, which is 3 x − 1 0 x − 6 x = 1 5 x .
Since the number of female doctors is equal to the number of male doctors, the number of female doctors is 1 5 x .
The probability of being a female doctor is therefore x 1 5 x = 1 5 1 ≈ 0 . 0 6 6 6 .