Mathematics 1228A/B Study Guide - Midterm Guide: 3 Women, Dharla River

• School: Western University
• Department: Mathematics
• Course: Mathematics 1228A/B
• Professor: All

Document Summary

[ 1 mark ] if n(a) = 25, n(b) = 47 and n(a b c) = 14, nd n(a b). Solution: we use n(a b) = n(a) + n(b) n(a b). We know n(a) = 25 and n(b) = 47. We weren"t directly given n(a b), but we know that of the 25 elements of a, n(a b c) = 14 of them are not in b, so the other 11 are. That is, n(a b) = n(a) n(a b c) = 25 14 = 11. So we get n(a b) = n(a) + n(b) n(a b) = 25 + 47 11 = 61. [ 1 mark ] there are 2 left-handed girls and 21 right-handed boys in a classroom. Solution: we know that there are 19 girls, so we just need to nd the number of boys to add to this. Since there are 5 left-handed students, with 2 of them being girls, the other 3 must be boys.