There are 2n subsets and 2n-1 PROPER subsets, where n is the number of elements. The empty sub The only IMPROPER subset is the set itself. How many proper subset do the following sets have? a) A={7,11} A has 2 elements so there are 22-1 = 4-1 = 3 PROPER substers. They are { }, {7} and {11}. ---------------- b) B={a,b,c,d} B has 4 elements so there are 24-1 = 16-1 = 15 PROPER substers. They are: 1. { } 2. {a} 3. {b} 4. {c} 5. {d} 6. {a,b} 7. {a,c} 8. {a,d} 9. {b,c} 10.{b,d} 11. {c,d} 12. {a,b,c} 13. {a,b,d} 14. {a,c,d} 15. {b,c,d} Edwin