3.33: Groups from a class and 5-character codes
(a)[3]
A class contains 7 girls and 8 boys. A group of 6 is selected from the class. The group must contain at least 3 girls and at least 2 boys. Find the number of different groups that can be selected.
(b)[3]
A 5-character code is formed from letters A–F and numbers 1, 2, 3, with no character repeated. Find the number of different codes that can be formed using 4 letters and 1 number.