We consider 3 different elementary schools E, M, S. The percentage of pupils wearing glasses is 10% in the school E, 25% in the school M and 40% in the school S. Compute: 1. The probability that by choosing randomly 3 pupils, one out of each school, at least one of them wears glasses. 2. The probability that a pupil wears glasses, if we randomly choose her or him out of the three schools (each school can be picked up with the same probability). 3. The probability that the pupil belongs to school E, if she wears glasses.